I was just looking at some of the electronic and boost activated cutouts, like the QTP one and such and i was wondering:

Would it hurt anything engine/turbo wise to go from decent back pressure, to almost no back pressure with the cutouts? I know turbo likey no BP in exhaust, but when your changing back and forth every so often?
Then also, if your tuned with the cutout open then close it, or vice versa. is that a problem?


I was searching threads, seems like everyone that has one is pretty happy so i guess it's just some weird paranoia of mine, just figured i'd ask though.

 

On a turbo car all the backpressure would be kept between the turbo and the head. After the turbo you aren't going to see any "scavenging" or any meaningful backpressure. Only thing I would be worried about is possibly a boost spike from the gasses releasing much faster. Goodluck

 

I run a qtp on my car, 3" downpipe with the cutout welded into a test pipe

the stock catback is pretty free flowing, so you can get on it with the cutout closed without too much of a problem

just get it tuned with the cutout open and don't do any serious racing unless its open

 

If you are tuned with the cutout open and run it hard with it closed you will just go rich so that not too big of a problem. If you tune with it closed and open it up you may go lean due to less backpressure.