They are cool though if you dont have emissions in your state. If you understand how a cat works, youd better understand how a TP works. There isa metalhoneycomb filter type element in the stock cat that absorbs and burns offmost of the polutants your engine makes after burning/combusting fuel/gases, etc before it is expelled from the exhaust. A test pipe is just a hollow pipe. Because it has no honeycomb, and the diameter of the pipe is (usually) bigger than the stock cat, exhaust flow is highly increased, and back pressure is decreased which = more power. You do need some back pressure for the turbo to be efficient, so if youre using a TP w/stock k03 turbo, youd want to keep the stock exhaust (test pipe back) or do no larger than 2.75" diameter piping on an aftermarket exhaust. Because of the better flow, the turbo should spool up a little quicker and you get a good bump in torque in mid range rpm's. It doesnt add a lot of hp, maybe 5-10. The tq is the main benefit. The only bad side affect can be the smell of fuel, mainly when you are just sitting-idling with the windows down, or right after you get out of the car. A positive side affect is turbo spool noise. It whistles a lot louder, and exhaust tone is more deep. Instalation is a pita for most people, but its not imposible. Now go search.
Actual HP/TQ gains will vary depending on your other mods. You will notice a real seat of the pants gain.Big TQ gain in lower RPM's and faster spooling. I have had mine in for a few months now and love it.
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2001.5 S4 6spd
GIAC, forge DV's, 3" cat back, short shifter, black Flik 18's.
i love mine too but it was a pita to install and it helps out alot if you have someone help you installing the test pipe
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01 Audi A4 Quattro, Mystery chip, Abd intake, Bilsten sports, H&R springs, Neuspeed front and rear sways and exhaust, Atp test pipe, JHM linkage, complete rs4 body kit, 18" Falkens, Nitto invo tires, Forge 007 and unos Mbc, 034 street trans mounts.
test pipe ?'s
