So putting the cutout before the rear axle actually gets better performance than right behind the headers due to too little backpressure? not to mention the noise factor. I saw this on the drag racing thread but it went to hell when people were bashing each other so i was hoping the ls1 guys could help me out.

 

I guess im asking...cutout after the cats is better performing than before them?

 

Big disagreement over that question. I would tend to think you get the most power with cutouts before the cats but after getting mine put in just this weekend and seeing the space limitations I had to put mine after the cats. Besides that if you have stock cats and y-pipe I think your only option is the i-pipe under the rear seat.

Good luck getting a straight answer.

 

thanks for the info...did you still notice a pretty nice improvement with them after the cats>?

 

It had a decent gain for the money. I'm gonna take it to the track when it opens and run it to see what kind of times I get open and closed. I might try to take it out on a empty stretch of road and see how it is once the weather clears up some. One thing I can say for sure is its a helluva lot louder.

 

Under the rear passenger seat seems to be the most popular location for mounting a cutout. That's where I put mine. Plus, if you go with an electric cutout, there's a grommet right there that you can use to get the wiring into the car. Also, the cavity where the seat is allows you to protect the electronics and motor from scrapes and speed-bumps.


As for a HP gain ... I picked up 13 RWHP just from opening the cutout. This was a controlled test on Hypertech's DynoJet.

 

Over the Stock WS6 exhaust?

In theory the gains might be even higher for a stock z/28 or T/A exhaust then, since they are more restrictive (mostly after the cutout location, since both cars share the same Y pipe).

I dont know why there is so much debate on the location. It would be nearly impossible to put a cutout before the cats on a LS1 car, and the top end gains would be trivial compared to the cost of fabircating a good escape route for the gasses from a precat cutout.

 

yup