I was looking at the Borla cat-back exhaust ($1050). Watched a video and it sounded pretty tough. My question is; given that the 335 has turbos, does the fact that you are putting on a freer-flowing exhaust discombobulate the tuning of the motor? I know that turbos need some back pressure, and I know that some of that it provided by the catalytic converters, but does this free-flowing exhaust negatively impact the turbo's performance?

If not, $1000 seems like a good deal.

Do the benefits of letting the motor breathe outweigh the negative impact on how quickly the turbo spools (due to lessened back-pressure)? :cheeburga

Don't do it for the performance, I don't think its there. But if you want sound exhaust is the only way to get it.

Thank you :)

I just put the Borlas on my car. I did the catback system. I chatted with the dealer about it before the installation. They were of the opinion that if you left the catalytic converters and downpipes alone, you should be okay. I didn't notice a turbo lag after the install, and it seems a little stronger. I have 644 miles on it presently, so I am keeping the RPM's at 4000 and under for the break in period. Putting the Borla system on shave about 40 pounds off the car, the stock mufflers are a lot heavier. It also becomes a true dual exhaust with a Borla system. The stock system has a vacuum valve that opens the left exhaust as needed. Now it is full open all the time.
I recommend the Borla system, you get crosswise looks in traffic when you are going down the road. There is a little more rumble in the aft floorboards as well. Sweet, the car is a little meaner. I can't wait to hit the 1000 mark and put in the Turbo Tuner.... Ka CHOW!

Seems to me that for power get Terry's black box and some downpipes. Maybe and intercooler if you want to get crazy. Exhaust seems a bit unnecessary unless you want weight reduction.

Reduction of back pressure does not hurt turbo's. Turbo's don't NEED back pressure. In fact, anything you do to relieve the back pressure only helps. That being said, if the stock exhaust with the open butterfly flows pretty freely, then there isn't much benefit to be seen.

Reduction of back pressure does not hurt turbo's. Turbo's don't NEED back pressure. In fact, anything you do to relieve the back pressure only helps. That being said, if the stock exhaust with the open butterfly flows pretty freely, then there isn't much benefit to be seen.

The flap on the stock unit is open when WOT, and therefore it's usually always open, there will be no difference because on the dyno it's open all the time.

As for back pressure, it sure does affect turbo performance. Turbo's are load based and the slight increase in load by a more restrictive exhaust should make the turbos spool quicker. If anybody can actually tell the difference is a different question, but just having 10" tubes for exhaust doesn't make more power. It's a tuning science of flow rates.

As for back pressure, it sure does affect turbo performance. Turbo's are load based and the slight increase in load by a more restrictive exhaust should make the turbos spool quicker. If anybody can actually tell the difference is a different question, but just having 10" tubes for exhaust doesn't make more power. It's a tuning science of flow rates

This couldn't be any further form the truth. Turbines are an energy recovery device. They do this by extracting the energy released from a pressure drop. The energy recovered is a function of the pressure ratio (if you want the equation, I'll give it to you). As you add back pressure, you reduce the available pressure ratio, so you reduce the energy the turbine can give to the compressor, so you reduce boost and the time it takes to spool the turbocharger.

If you look at all out turbocharged racing engines (F1 from the 80's, drag racers, drag boats, Champ cars), all of them have a large diameter short pipe after the turbine to get the exhaust to a safe place to dump it... and that's it. Probably no measureable back pressure.

I'm interested to see which it is

JB2, Downpipes and a good Intake or K&N filter should do it for starters. I would like to read more on downpipes vrs exhaust?

I'm feeling that to, the exhaust seems adequate but dumping those stock pos down pipes would be hugely benifitual in both HP and reduced under hood temps and turbo temps. Down Pipes on my WRX (eliminated 2 cats) was worth like 20hp suposedly, not sure it that's true or not but after i installed it, the car felt crisper and faster.

Wow, so much bad information in here. My last three cars have been turbo, all over 300 whp, so take it from someone who has actually tuned turbo vehicles, turbos do not need backpressure. Engines do require alittle backpressure, fully opening the exhaust on a naturally aspirated car is not a good idea, and you will lose alittle bit of torque at lower rpms. With that being said, on a turbo'd engine, the turbos create alot of backpressure for the engine regardless of the size of exhaust. Putting a larger exhaust on a turbo'd vehicle will decrease spool time by reducing the amount of pressure put on the turbine wheel. Turbo engines benefit the most from large exhausts and see good gains anywere from 5 through 40+ hp in some cases.

You want to know the -'s , the -'s are the $ you are going to spend, and a louder exhaust note (if you consider that a - ) Hope that helps.

BTW, Good choice with the Borla, they make the best exhausts :)