98 Ls1

Ddoes anyone know what size cutout will fit my stock LS1 best? I kinda wanted to go for a 3 inch, but I'm pretty sure the stock I pipe is 2 and a 1/2... right? Will it fit?


http://www.jcwhitney.com/autoparts/Product/tf-Browse/s-10101/Pr-p_Product.CATENTRY_ID:2009999/showCustom-0/p-2009999/N-111+10214+600012933/c-10114/TID-8014524

BTW I heard under passenger seat, after cat was a good place to put it, but will it mess with my o2 sensors at all? or will I have to fix that problem?

Go with the one that is the same size as your stock pipe unless you want to really modify shit to make it fit, and wwhy go through the cat with it? Why not just put it before the cat if you can?

well, a few knowledgeable guys at ls1tech told me that the best spot for a cut out was right after the cat under the passenger seat. It also sounds great cause at least the noise is filtered through the cat. I don't exactly want to run open headers, and I plan to keep the lid off of the cut out 99% of the time