If you are leaving it stock, I would agree with helivaguy and go with the 053 or 086. The JP4 also isn't too bad but definately not as strong as the JP1 or 2. If you want to get it race ported, I ran one the last 2 years with a JP1 and had more power than I needed and got between 9:30 and 10:30 consistantly so the rumors of the JP1 not being fairly fuel efficient are not totally true when talking about full race porting. It is definately not the best pipe out there for milage but it isn't that bad either. The P5's I have done with the same race porting as mine but ran pipes like the 9901SS/41021 or 9853SS were getting 11+ minutes so again there is even more room for improvement but fo r someone who has pipes already, there are certainly alternatives available to get the performance with run times with the equipment you already have. You can get a full blown P5 with a front ceramic for around the same money as a stock plus 4. Let me know if you are interested in something like that