I was wondering if it was safe enough to run just a down pipe on my car. If i do this will it have enough back pressure? Some people told me it would and some said it wouldnt. What do yall think?

 

ya just make sure u run it so blows the exaust out the engine bay, or ur just gonna be sucking exaust back on the turbo, and making one hell of a mess in ur engine bay!

 

yes, look at most cars that drag race.
backpressure is bad for FI

 

yea you can run just open downpipe, look at my avatar, it comes out the bumper.

 

i've been running open dp for over a year.. sounds awesome WOT

 

if your car was tuned with 3'' exhaust. will it affect the tune to run it oped DP?

 

yeah, but not enough to hurt anything..

 

Actually...it might. There will be a little less backpressure, in the end that leads to leaner AFR's. If its temporary, just don't push it hard, only a few psi max. FYI the turbine itself is usually enough of a restriction for light throttle cruising.

 

I ran open DP for 6 months, it sounded mean. I got followed all the time by cops. And then one day i got pulled over and got a ticket for "defective exhaust", i just told the cop that i had to pull the muffler off because it was rusted. Thankfully he didn't bother looking underneath the vehicle, because i could have gotten a ticket for no cat.

I then put a straight through 3in exhaust and it quieted it down. Open DP is fun, but if your state has strict emission laws and regulations i wouldn't risk it.

 

If you send it out the bumper instead of under the car its a lot quieter and doesn't 'drone' as much in the cabin.

 

I've ran an open DP on all my turbo setups and I've ran an exhaust once. The day I pulled the exhaust I was running off. It free'd up alot of power. I can't say my exhaust flowed the best but running open Dp flows excellent and sounds nasty. Plus as stated the turbine should cause enough back pressure for the application. It's not as loud as you think it would be especially once you get into boost. It's nearly quiet.

 

my car is pretty loud open downpipe.

 

On some cars it sounds gay imo.

I had a cutout on my 99 Si w/a b16 and 57 trim running a full 3" exhaust. I didn't gain any whp, but only around 10ft lbs when the cutout was open. This was on a dyno. The car was making 450whp @ the time.

 

I thought some back pressure was need for the turbo??

 

For a NA car not having enough back pressure can have a major negative impact on performance. For a FI car however you really don't need much at all, almost in any case less back pressure will result in more power. There are always some exceptions to the rules however.

 

I think cut outs tend to cause turbulence and don't create the power that a true open dp does.

 

How would you tune the car if you have a cutout? What if you wanna do full boost with cutout open, but also do it with the cutout closed. Can you do that or you must tune just for 1 of the scenerios and never ever full boost in the other?