im looking at the carsound cats on ebay right now...i got my jethot LT"s and getting a Ypipe made..But a 3" cat wil fit a catback right? or do i need the 2.5"..lil confuesd on that

 

The cat will go somewhere in your y-pipe. The collectors on your headers are 3" so I am going to assume that the shop is going to make you a custom y-pipe that will be a 3" diameter as well. If so, the 3" cat will fit in there perfectly.

 

Here's what I wanna do...i wanna put the Elec-cutout in too, will there be enough room for a cutout and a cat like i have drawn out???