wow your lucky! no cats yumm... i really dunt think its a good idea on a stock or near stock p10 or p11, the amount of back pressure u lose is just too great. Unless you have a SR20DET in there then yeah put a down pipe on it. im NOt sure how it would sound but i myself would definitely not straight pipe it. and i think people replace it with a highflow cat, but im not sure the power gain/loss wise with that.