E90 335i, Borla cat back. First to Dyno!

HP Autowerks, Inc's 2007 E90 335i was the test bed for the Borla cat back stainless steel exhaust. The prototype was completed and tested last Friday. The first production model is currently on our vehicle. Full release of this system may still be weeks away, but we will keep you guys posted. The system consists of two sections, a built-in X-pipe mid section and a rear muffler. See photos below...

The exhaust tone is a little bit deeper than stock. Now, you can actually hear the exhaust, but just a hint of it. There is no resonance with this exhaust at any engine rpm or load. For those of you who is not a big fan of loud and annoy resonant exhausts, but still want significant performance gains, this Borla is for you! Did We forget to mention weight savings? We will post the numbers as soon as the Borla engineers release the information to us.

Today we dyno the Borla cat back and compared it against our baseline numbers. Dyno runs were done on Dynojet with no cool downs in between runs, BMW seem to like it hot, and our E90 was no exception. Our E90 335i has just over 2000 miles on the clock, easy break-in until 1000 miles, and oil was changed with Redline 5W40 full synthetic motor oil.

Baseline: Max Power = 249.47 Max Torque=290.54

With Borla Cat. back: Max Power = 280.94 Max Torque = 300.09

Wow!!! A gain of over 30 HP!!! With almost 10 ft lbs of torque to boot! And it was almost 20 degrees warmer today!

During the same dyno session, we installed a HP Autowerks custom tri-foam high-flow air filter element. Yes, just a drop in replacement, anyone can do it in less than a minute. Okay, maybe two! Without time to allow the computer to learn and adapt to the added airflow provided by the new high-flow air filter element, the number kept on climbing on the dyno with each pull, on the third pull we got...

Borla with HP's Filter: Max Power = 284.24 Max Torque = 300.72

Nearly a 4 HP gain at the wheels just by replacing the stock paper air filter element with HP's custom high-flow filter. We are sure the numbers will be slightly higher if there was more time for the computer to learn and adapt to the added airflow. A custom CF airbox lid is in the works to improve airflow and volume further, so stay tuned!!!

Please feel free to contact us with any questions you may have. We will post the release date as soon as we know and start taking pre-orders at that time. If you are in Santa Barbara, feel free to stop by our shop at 515 Fig Avenue and have a look at the Borla exhaust for yourself!

High-flow tri-foam replacement air filters are available now with two to three weeks production time, as each filter is hand-made.

E92 335i version of the Borla exhaust should net very similar results.

249.47 baseline? That sounds very low.

I frequently have seen manufacturers claims of 25+ HP with catback exhausts but the most I have ever seen in the real world is about 5 HP max.

Originally Posted by Andre

249.47 baseline? That sounds very low.

Remeber, this is the number at measured at the wheels. In addition, the number is really relative, it is the gain you really should be looking at. Look at the torque, 290+ ft lbs at the wheels, stock!

Originally Posted by Larry Clemens

I frequently have seen manufacturers claims of 25+ HP with catback exhausts but the most I have ever seen in the real world is about 5 HP max.

If after market exhausts can pump out another 10 to 15 hp out of the s2000 2.0 liter N/A engine to the wheels....dyno proven!!!!! Then 25 to 30 on a Turbo car is not out of the question. Actually 25 hp out of a turbo car from a new aftermarket exhaust is not unusual!

Is there any indication of pricing?

Given the economy of muffler cans in the picture, can we expect a price that's lower than that of the 2-muffler-cans systems already in the market?

Please keep us posted...

Originally Posted by Andre

249.47 baseline? That sounds very low.

Yes the lowest 335i dyno Im aware of by 20hp! I wonder if the 335i dual exhaust is already optimized, its a true dual exhaust. I also remember reading somewhere that direct injected turbos are not really enhanced by a lower backpressure exhaust systems as its not a limiting factor with engines that control fuel and air separately, as only direct injected turbos can. I smell a rat here.

I am a big fan of Borla..... I would like to see / hear this once it comes out.... Is it a bolt on or does it require modifications?

Also, are there any plans of making an adjustable system like they have for LT1 / LS1 F-Bodies?

Originally Posted by desertdriver

Yes the lowest 335i dyno Im aware of by 20hp! I wonder if the 335i dual exhaust is already optimized, its a true dual exhaust. I also remember reading somewhere that direct injected turbos are not really enhanced by a lower backpressure exhaust systems as its not a limiting factor with engines that control fuel and air separately, as only direct injected turbos can. I smell a rat here.

one thing not mentioned is what dyno. mustang dynos, for example, are known to be conservative #s wise, while dynojet is usually regarded as more agressive as far as #s go. some dynos are load bearing (trying to better simulate street conditions) while others aren't. hopefully this can be clarified!

I had a B&B exhaust on my 330i, and I currently have a FabSpeed on my Porsche. My brother had a Borla on his 330i ZHP.

By far, the nicest sound and least resonation was found on the Borla. I trust those guys (and they are local for me).

What is the weight difference?
It is bolt-on?
How much is it?

- Mike

How is fit and finish?

The pipe on the right side seems to be way off center from the rear bumper port.

Originally Posted by coloradosilver

How is fit and finish?

The pipe on the right side seems to be way off center from the rear bumper port.

id say a minor adjustment of the hangers could recitfy that pretty easilly.

what sucks about stainless exhausts is that they need to heat cycle several times to be 100% sure fittment is as desired. i had to adjust mine several times after it was installed to keep it looking right. after a couple of weeks it finally settled down as looks perfect!

although i dont have a borla on my a4, they enjoy a nice reputation in the audi community for a quality product for sure!

Originally Posted by DenverNoob

one thing not mentioned is what dyno. mustang dynos, for example, are known to be conservative #s wise, while dynojet is usually regarded as more agressive as far as #s go. some dynos are load bearing (trying to better simulate street conditions) while others aren't. hopefully this can be clarified!

Actually, we did mention what dyno was used, dynojet.

Originally Posted by coloradosilver

How is fit and finish?

The pipe on the right side seems to be way off center from the rear bumper port.

The fit and finish is great. The photo probably threw everyone off a bit since it was taken from an angle. We will post more photos soon.

Originally Posted by HP Autowerks

Actually, we did mention what dyno was used, dynojet.

oops....just kidding. ill go home and learn how to read tonight! lolol.

glad to see some GIAC in the house! im a big fan!

Originally Posted by TTG

I am a big fan of Borla..... I would like to see / hear this once it comes out.... Is it a bolt on or does it require modifications?

Also, are there any plans of making an adjustable system like they have for LT1 / LS1 F-Bodies?

It is a true bolt-on after cuts are made just behind the second set of cats. Remeber, this system is smog legal, so no modifications were done to the oem cats.

Originally Posted by Emission

What is the weight difference?

How much is it?

- Mike

I will post the weight savings and price as soon as Borla release them.

Just received a phone call from Borla. The stock system removed from the vehicle weighs 59 lbs. The Borla system is much lighter, at 33 lbs. A weight savings of 26 lbs!

We can not confirm the pricing yet, but figure between $1095 and $1295.

Originally Posted by HP Autowerks

It is a true bolt-on after cuts are made just behind the second set of cats. Remeber, this system is smog legal, so no modifications were done to the oem cats.

I ask about "bolt-on" because my car is leased. My brothers Borla ('04 330i ZHP) exhaust was about $900 new. We bolted it on his leased BMW and he used it three years. We sold it used for $450, and bolted his OEM exhaust back on. It was a piece of cake, and all done in my garage, and BMW had no way of telling it was done.

If this requires cuts behind the second set of cats, it doesn't sound as if it can be done in the garage at home (at least putting the OEM back on), and there would be evidence to BMW about the alteration.

Originally Posted by Emission

If this requires cuts behind the second set of cats, it doesn't sound as if it can be done in the garage at home (at least putting the OEM back on), and there would be evidence to BMW about the alteration.

The cuts behind the cats are actually hidden from plain view(right above floorpan connecting support). Take a look at the photo with the crossover pipe. The black piece of metal at the bottom of the photo is the support I am talking about, it is about 8" in length(just a guess), and the cut is made right above that band style clamps are used.

If you like, schedule a time, come down to Santa Barbara and have a look at the exhaust.

Originally Posted by HP Autowerks

The cuts behind the cats are actually hidden from plain view(right above floorpan connecting support). Take a look at the photo with the crossover pipe. The black piece of metal at the bottom of the photo is the support I am talking about, it is about 8" in length(just a guess), and the cut is made right above that band style clamps are used.

If you like, schedule a time, come down to Santa Barbara and have a look at the exhaust.

I have a meeting in Carpenteria early next week. I just may take you up on that offer.

When posting high HP increases you will always have the nay sayers. It's not usually me, but in this instance it is. An increase of 30hp with just a catback exhaust seems incredibly far fetched. How many baseline runs did you guys make before doing the run with the exhaust? and how many runs were made with the borla exhaust? I've learned that when something sounds too good to be true...it usually is.

Originally Posted by Raz5219

When posting high HP increases you will always have the nay sayers. It's not usually me, but in this instance it is. An increase of 30hp with just a catback exhaust seems incredibly far fetched. How many baseline runs did you guys make before doing the run with the exhaust? and how many runs were made with the borla exhaust? I've learned that when something sounds too good to be true...it usually is.

3 runs each. The dyno chart tells the results. The Borla system lifted the hp and torque curve throughout the rpm range. A simple drop-in high-flow filter resulted in 4hp increase without time for the computer to adapt, results may be greater.

Originally Posted by HP Autowerks

Just received a phone call from Borla. The stock system removed from the vehicle weighs 59 lbs. The Borla system is much lighter, at 33 lbs. A weight savings of 26 lbs!

We can not confirm the pricing yet, but figure between $1095 and $1295.

I would be very skeptical of the claimed HP gain knowing that the factory cats are still in place. Typically on a turbo car that is the greatest bottleneck, and as someone already stated, the baseline number of 249HP stock looks a lot lower than anything else that has been published for a 335.

Unbelievable results.

Like I said, unbelievable.