In the world of BMW tuning, there are a few names that are more popular than others. From the top of my head I could probably name AC Schnitzer, Hamann and Manhart as some of the best in Europe, yet one that stands out constantly in the US is DINAN Engineering.

Founded by Steve Dinan back in 1979 and based in Morgan Hill, California, the tuner is a well-known company in BMW communities not just in the US, but also around the world. That’s mostly due to the great work, as they usually offer performance packages that perfectly complement the standard cars in the first place. And that’s something a lot of people tend to forget.

Tuning, when done right, is supposed to just enhance, offer a bit more flavor not completely change the character of a car. After all, customers are buying cars for a number of reasons but they do make a choice, picking a model that they think fits them perfectly. When you go ahead and change that car beyond recognition, the essence of it is lost and you end up with an unrecognizable version of what you initially wanted.

That’s why a lot of companies out there might offer power packages and other products for your BMW, but when they are actually done with your car, you might not recognize it. In tuning, pretty much, as it is the case in life as well, balance is everything, which is why a holistic approach will always be recommended.

Dinan does just that and it does it without turning your vehicle into an illegal contraption, one that breaks the law every time you start the engine outside of a race track. That’s because their offering is basically the only legit one on the market, the only one that abides to the 50 state emissions regulations, even in Stage 3 guise. And that’s something you need to remember, even though a lot of people simply don’t care about this kind of stuff, simply looking for more performance.

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Dinan’s Stage 3 kit takes it up to no less than 548 HP and 559 lb-ft (758 Nm) and that’s more twist than you’ll find on a BMW M5 right now


And while you may think that might take a toll on how much added power the car can gain while also remaining street legal, I’m here to tell you that the added oomph is more than enough for your daily needs. In standard guise the BMW M4 makes 425 HP and 406 lb-ft (550 Nm) of torque. Well, Dinan’s Stage 3 kit takes it up to no less than 548 HP and 559 lb-ft (758 Nm) and that’s more twist than you’ll find on a BMW M5 right now.

How was it all achieved? First you start with a new ECU tune developed specifically for the S55 3-liter twin-turbo engine under the hood of the M4, but that’s just a small part of everything that goes into making this a reliable tune as well. Because of the new parameters the car has to work with, you’ll also need a bigger, cold air intake as well as some extra cooling and a new exhaust, of course.

Dinan’s S55 cold air intake uses a sealed air box that prevents the intrusion of hot, under hood air thanks to its relocation to push in cold air. Air is passed through a 30 percent larger high-flow filter, past an upgraded MAF sensor and into a carbon fiber tube that provides 20 percent more air volume than the stock piece. This alone would give the engine max gains of up to 14 hp and 21 lb-ft of torque.

Then there’s the free flow exhaust system which features 16 gauge 304 stainless steel construction. Dinan’s Free Flow exhaust system features twin secondary exhaust valves with a whopping 76mm diameter, making them 45 percent less restrictive than the OE valves. Computer controlled valve actuation has been fully retained for a civilized low-volume experience in Eco mode and high-volume unrestricted performance in Sport and Sport+ modes. This combination nets the M3 and M4 five horsepower and a weight reduction of three pounds. This system was designed to produce a more aggressive sound too under acceleration something you notice in full once you’re out on the road.

The full kit also includes a new X-Pipe that removes the factory center section after the secondary catalytic converters, including the large resonator. In its place Dinan introduces straight through mandrel bent 2.75″ T304 stainless steel tubing and the custom ‘X’ for better flow, and an improved sound.

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Dinan put together a complete suspension kit to improve maneuverability and performance.


To keep the temperatures in check a new heat exchanger is needed offering 60 percent more core volume and 19 percent more face area than stock. Being 16mm thicker than the stock cooler, a 9° average water temperature reduction is offered to the intercooler across the RPM range. Colder water improves intercooler efficiency and allows the intake air to be cooled by an additional 6° average across the RPM range compared to stock. This leads to significant reduction in the tendency to heat soak.

All these upgrades will take care of the power aspect of the car but as I’ve already mentioned, this approach had to be holistic as all that extra power needs to be kept in check. One thing people complained about when the M4 came out was the fact that the car seemed to be too snappy compared to the outgoing E9x M3 models. Part of that issue was due to the turbocharged mill which, once spooled up, offered considerably more torque than before, meaning the rear axle would simply start spinning out of control if you’re not careful with the throttle.

To address these issues, Dinan put together a complete suspension kit to improve maneuverability and performance. The rear axle received special attention, the complete suspension link kit taking care of those issues, a must-have if you increase the power output of the car by so much.

The stock rear toe link is built with rubber bushings and a curved forged alloy rod which can flex. During hard acceleration, this flex allows the rear wheels to have excessive toe change under hard acceleration and braking. All of this flex in the stock toe links causes the car to be unstable. Dinan stops the flex by replacing the rubber bushings with Teflon coated machined steel rod ends and the OEM curved bar with a straight billet aluminum rod, thus adding stability.

The Dinan rod-ends incorporate left and right-hand thread, which allows quick and accurate toe adjustment that is tough to achieve using the stock system. Like the rear toe links, the stock front trailing links also incorporate rubber bushings.  Flex in these bushings allow the rear wheels to behave sloppily under heavy loads.  Dinan adds precision by replacing these links with billet aluminum rods and Teflon coated machined steel rod ends.  These front links are not adjustable.

Then there’s the Dinan tension strut ball joint kit that replaces the rubber bushings in the thrust arms with precision ball joints and machined aluminum housings thus improving responsiveness by eliminating the deflection inherent in the stock rubber bushings while also reducing brake shimmy. Furthermore, the complete kit includes lightweight tubular anti-roll bars that truly make a difference in the car’s behavior.

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The cold start was even more impressive as the car was parked in a garage…


They measure 32mm in the front and 24mm in the rear, saving weight and offering an adjustable setup for those wanting to fine tune their car’s handling. There are four adjustability points on each end that work with the adjustable end links for a total of five positions on the bar, making it adjustable from 57 percent to 103 percent stiffer than the stock front bar and 0 to 13 percent stiffer than the stock rear bar.

Last but not least, I have to mention the adjustable coilovers. There is an abundance of models available for the M3/M4, including one made by Dinan. Their design keeps the factory Electronic Damper Control shocks in place and implements threaded collars to allow you to change the ride height. The end result is a sleek lowered stance that provides improved handling along with a better look in my opinion. Unfortunately, the car we tested didn’t come with EDC so we were basically stuck with one setting that proved to be quite harsh on my back during the first days with the cars. LA roads aren’t exactly the smoothest out there.

The springs combined with progressive bump stops and other components increase travel that allows the car to be lowered up to 1″ in the front and 1 1/2″ in the rear, with spring rates being increased by 50 percent in the front and 10 percent in the rear. Suspension packers are included to fine tune handling and comfort by changing the clearance of the progressive bump-stops.

All the parts listed here create a package that is hard to beat these days. Going to pick up the car all I could think of was whether I would truly notice the big changes the company claims or whether all of it would be just hot smoke. As it turned out, I was impressed by the way the Dinan S2 handled and there’s more to it than meets the eye.

The first thing you notice is just how different the engine note is. The cold start was even more impressive as the car was parked in a garage and the sound of the exhaust resonated against the bare walls, truly making it a gearhead’s delight. The upgraded exhaust sounds so good that it turned every tunnel I went through into a proper exercise of will, trying not to pop the car in neutral and let it rip to hear its majestic burble.

I decided to be brave and take this 550 HP beast out on the road, to see exactly how much and more importantly how its character has been changed, expecting the rear end to be as playful as a Labrador puppy. However, I was surprised to learn that the Dinan S2 can be both quite docile as well as a ferocious beast. First of all, I took full advantage of the M1 and M2 buttons on the steering wheel, setting up M1 in the most docile setting (Comfort steering, level 1 gearshifts for the DCT, efficient setting for the throttle response) and the M2 in full attack mode.

Using M1 showed me that the car is actually usable on a daily basis. The pedal response is docile and doesn’t get the car bucking as soon as you touch it, while the steering is not as hard as trying to grind wheat using your hands only. The only gripe I had was the suspension which, in the standard M4 without the EDC stands somewhere between the Sport and Sport+ setting. Well, the car I was driving had all the suspension changed to be more track focused and therefore I could literally feel every crack in the road. And I mean every crack in the road. The 20” forged wheels and their Pirelli Corsa tires didn’t help a lot to alleviate this situation either, but they did play an important role when I took the backroads and used the M2 settings.

The standard M4 comes with 18×9 inch wheels and 275/40 tires on the rear. The car I was driving was running 20×9.5” wheels with 305/30 Pirelli P-Zero Corsa tires on the back, not helping in terms of comfort, but making a huge difference in terms of grip.

Once I started pushing the car closer to its limit, I was surprised to see the extra grip compared to the standard car, and all that with over 100 HP extra and impressive torque. It wasn’t just the wheels that made a difference, but you could also feel how the new suspension setup changed the character of the beast, keeping it well in check. Understeer, at least on public roads, is a thing of the past. Sure, you may find some of it on the track at some point, but it will take a 10/10 push to do that.

The front axle gripped like crazy and made turn-ins a thing of joy every time I approached a tight curve in the road with way more speed than I should’ve. The car handled everything I threw at it with ease, seemingly teasing me as if it was saying ‘Is that all you’ve got?’. The M4 S2 was absolutely planted in every situation, but the biggest change I noticed was the fact that it didn’t break traction as easily as the standard M4.

That’s notable for a number of reasons. It’s not just the overall feel of the car that had been improved but it’s important to note how it changed as that is what makes the difference between tuners. The whole car felt just as if it was a lot more aware, more connected to the road in every sense and a lot faster without making me wonder about what would happen if I suddenly flew off the road as that didn’t really seem to be a possibility. I guess what I’m trying to say is that the Dinan S2 M4 showed me just what a ‘confidence inspiring’ tune really means.

And that’s just what every tuned car out there should be. That’s what you should aim for when trying to improve your car, focusing more on performance than on everything else. Sure, there will be some drawbacks but they simply can’t be avoided. To put things in perspective, think of it this way:

BMW creates M cars to be a perfect balance between every day usability and track days. Imagine a scale that holds comfort on one arm and performance on the other. Once you choose to tune your car, the balance of it will tip to one side or there other, most likely towards performance. So you will lose some of the comfort but if performance is what you’re after, you can’t really complain.

That’s what Dinan is offering: performance tuned to your needs. And that’s what makes this car and the kit on it so appealing. The overall price of everything you see installed on the Sakhir Orange M4 adds up to close to $90,000. The car itself was about $67,0000 and then you add about $20,000 in upgrades coming from Dinan. The beauty of it though is that you don’t need all of them, but you can choose what you want to upgrade.

The S2 package adds up to $13,282 and includes the engine tune with the exhaust, intake, heat exchanger ($9,269) and the complete suspension upgrade for $3,874. Of course, you can install them in stages. My suggestion would be to start with the suspension to see exactly how it upgrades your car. Then, I promise you, you’ll want more power to match the newfound capabilities of your car’s chassis.

The rest of the money up to $20,000 goes into accessories and wheels, the latter alone costing $6,550 for the set. They are forged and they are lightweight but you really need to stop and think about whether you really need to spend that much on rims. You might be better off with choosing the brilliant Competition Package wheels that look a lot better in my opinion. Then again, another good thing is that Dinan claims you don’t have to upgrade the brakes on your car and therefore, you don’t need wheels larger than the standard 18” ones. According to them, the car I drove was a R&D model that used the standard brakes and never showed any need for some extra stopping power, despite the HP increase. That says a lot about the great work BMW did when fitting the M4 with proper disks and calipers.

If you’re just looking to tone down the uncontrollable spinning rear wheels of your stock M4 you should also consider at least part of this kit, as it truly makes a difference where it matters. To top it all off, you get to keep your warranty intact, something no other tuner in the US is offering.

A lot has been said about the way the warranty works, but according to Dinan things are very simple. You can have all these parts installed at a select BMW dealerships and this won’t void your warranty. In case something goes wrong with parts installed as part of the Dinan tune, the people in Morgan Hill will take care of it. Then again, due to the special relationship Dinan has with BMW North America, if anything not related to the tune breaks on your BMW, your car will be covered under the standard warranty, no questions asked. It’s that simple. The coverage expands over 4 years or 50,000 miles.

So where does that leave us? Is the Dinan S2 M4 worth the extra money? Well, it all depends on what you’re looking for and what you’re planning for your BMW. If you want to keep up with much more expensive cars on the track or even on the highway at eye-watering speeds, this is a great way to go. The added power and control the kit offers may turn this thing into a back-breaker while it will also offer you the edge in terms of performance, without too much hassle or worrying about your warranty. In the end, while the power increase might seem like the biggest plus of the whole package, it’s truly the chassis work that shines when behind the wheel of the Dinan S2 M4 and that’s something you need to remember as nobody ever complained about the S55 engine not having enough power in the first place.