Re: Cutout location?
Actually its not just a "more power" issue, the 12" is to ensure that you don't suck fresh air in at idle and confuse the O2 sensors, which will throw the car into limp mode. I am facing the same decision making process as you, and at the same time trying to make a "quick swap" setup with flanges, so the race pipes/cutouts can be removed, either for temporary cat install for inspections, or to do work on the engine, etc. The problem is fitting everything. If you put the cutouts where the race pipes would normally go, you're at like 8 or 9 inches from O2 sensor to opening of cutout. Not 12, but also not 1 inch like running open headers is (which is the only time I've heard of the "limp home" mode happening). The other option is to weld cutouts into the Y pipe, probably on the inside for clearance, and leave the race pipes in. I'm still trying to figure out how to make it all work.
I've got dual Qtecs, dual cutouts, and lots of 3 bolt flanges, and even a spare SLP 3" Y-pipe sitting on the floor here, just trying to figure how to make it all fit.
-Dave
-Dave