hey i am a ford tech and have installed a few performance upgrades in my day, ussually on mustangs well install 4:10 gears or a catback exhaust but only see about 15 to 25 hp gains from the cb. first what could i expext from my 07 2.0t 6sp man with just a cat back, also are their gear swap sets available for the quattro!!??

 

As far as gears go, Stasis engineering sells a center differential that makes the four wheel drive an 20/80 split so it feels and drives more like a rear wheel drive car, instead of the 60/40 thats currently in the B7 A4. Im not sure if they sell gears, but thats useless on the type of car you have, great for a mustang though.
A catback exhaust will yield different gains, it depends on what mods are done to the engine. If its just stock you can expect about 7-10 horsepower gain. If you're running a garrett GT28RS turbo then you can expect around a 20-30 horsepower gain over stock. Although i doubt the engine would run very well with a stock exhaust and that turbo LOL. Also, since i know you're back ground, forget about X pipes or H pipes on this car.

 

i like the idea of the 20\80 split but wonder if it would take away from the awd or maybe even confuse the esp?? also seing how the car is a 4 cyl how would a H or x pipe setup apply? when i did the inspection i notice the stock muffler is one port in to a dual out, also with just a catback what size pipe should i shoot for 3inch or is a little restriction 2.75 ? ok thats if i decide to run the pipe myself. i remember something about turbo motors and restriction in school but the only turbos i work on come off diesels lol with 3.25 exhaust.

 

The ESP is based off of wheel speed sensors, it doesn't care which wheels are driven. If one or two of them slips, it will engage the traction control regardless.
You don't need a H or X pipe with a force induction engine. Larger straight through pipe is your friend. Just study all the aftermarket exhausts for turbo cars, usually you will have a 3" downpipe from the turbo back and it will either stay 3" or go down to 2.75" or 2.5".
The larger the pipe the louder of course, but you need larger pipe if you plan to increase the boost/airflow, especially if you plan to upgrade the turbo in the future. Having a little back pressure is important, but the turbo itself will generally give itself enough back pressure to run on a 3" exhaust all the way back. The smaller you make the pipe, the faster the turbo will spool, but if you make the pipe too small, you will limit your horsepower.

 

that makes sense, i remember my instructor telling me that. and i realize the esp is a tone ring based system i just am amzed at the ability of the system to correct my sideways slides through corners as i try to power through, i think its saab that uses a power based correction sytem to correct traction issues, where i noticed my b7 applies brakes and limits the power to certain wheels, same as in ford TA equipped vehicles. I will probably run the exhaust 3" all the way but will i need to install a HFC, i think those are really just propaganda or am i wrong? ive seen a friend install a HFC on his prelude at school we did a before and after on the dyno and whadda you know no difference! i also worry about emmisions because i cant loose my state inspection liscence or im screwed for my job!

 

No a high flow cat is a great upgrade on a turbo car, and one of the members here Mike2ptzero can sell you one at a decent price if you PM him. He might even jump in here and show you one. He just posted a pic of the one he carries in a horsepower thread not too long ago. A 3" testpipe (no cat) is even better. It won't do squat on a prelude.

 

well test pipes sound great except i likemy ecu and o2s to not hate each other, i heard wth stage2 apr u dont need to worry? any truth to this

 

Yes, most chips will eliminate the use of the rear O2 sensor removing the cat efficiency fault.
You could also jerry rig a couple spark plug non foulers to provide a spacer between the pipe and O2 sensor. That usually only works for a while though.

 

yea i tried the spark plug non foulers on a sonoma i removed the cat from, it worked fine in the summer but for some reason i couldnt erase the code fast enough in the winter, thanks for all ur help

 

A HFC on a 2.0t can make a big difference, some have even done testing to see a 33whp and 27 ft/lbs TQ gain on a stock turbo tune. It helps to reduce the back pressure at the back of the turbo exhaust wheel and allowing the turbo to spool much easier and faster in the higher rpms.

If you are in the market for a full exhaust ER plans to release their B7 A4 2.0t exhuast soon. I am just waiting for them to send me pics.


As for the torsen mod, it only changes the car during high load, so basically when coming out of a corner under power and decel. Any other time the torsen acts the same as stock. It is not going to make your car feel like it is RWD when launching or driving in a straight line.