colonialcobra

I've noticed that many of the 4" exhaust systems have a 3" downpipe.
For a stock truck. How much difference does the 4" downpipe make?

They all note that spool is quicker off the line with the smaller downpipe.

Is it a noticeable difference??

Thanks
Brad

schoust

They run a three inch down pipe because that is what the stocker turbo outlet is. Before I went to the aftermarket turbo I had the same downpipe but when I went to the s300 variant it required an hx40 type pipe which is four inch. I will also say that three to four is not hurting the performance much since more than likley the stock turbo is still being run and there are limitations there.