ppl are recommending headers w/ 2.5" collectors.. does this bolt straight onto a stock gsr?

 

And a cat flange too if the cat you buy isn't already pre-fabbed with the 2.5" flange already on it.

Dave @ SMSP and Mike @ IPS sell the pre-fabbed Carsound units that are popular with the kids on this board.

jdmhondaparts, inlinefour, and I'm sure SMSP also carry the cat flanges separately. In that case, you need to find somebody to weld it onto the cat for you.

 

Just so you know, the welds from the cats @ IPS are impeccable. Im sure SMSP's are as well (just in case youre unsure about a local welder).