He's right, the force of the exhaust does add some downforce. There are many reasons for their exhaust being how it is, but I was exemplifying how they don't need backpressure to make the power because it probably isn't a hugely necessary component.


I run downpipes into test pipes into my catback (essentially straight empty pipes and a pair of resonators) and have had no issues.


Get rid of the AIV's, they're useless (Nissan acknowledged this in 92 or 93 when they themselves eliminated them from the production of the Z32). Remove the sensor in the engine bay and it's pertinent vacuum lines, remove the AIV solenoids from inside the wheel well (pull back the fender liner), and remove all the hoses connecting to the exhaust. Then get an aftermarket ECU (if you don't already have one) to eliminate all electronic signals that make use of the AIV's (all aftermarket ECU's eliminate the AIV's as well).

 

i'm going to have to find a write up on that. i've never even heard of that stuff. is there an easy bypass for it or does the elimination of the system require a new ECU? the car's not quite worth a new ECU. thanks agian for all the advise here. my car would probably be at the bottom of the river (intentionaly) without you guys.

 

You can probably eliminate it without replacing the ECU. As long as you disconnect the sensor, it should work out just fine. There are writeups on AIV elimination all over the place, so it shouldn't be hard to find more info on it.

 

alright thanks a lot. based on advise given here, i have decided to get test pipes made, eliminate the AIV system, and have my cat-back patched or replaced to eliminate the leaks. i'll let you all know how it turns out in a few weeks. i bet she'll be plenty loud then lol. its a bit too loud for me now!

 

they do, but not much. i was referring more to the funny cars. otherwise, why wouldnt they just be pointing straight out/down? (im sure theres more to it that just that)