Originally Posted by chopper82p

I don't want to argue or anything, just saying: when I put a P4 plug in my P5, I was able to clear a jump I wasn't able to clear before (the jump was beat up, track wasn't maintained for some time before that). More torque everywhere, a stronger idle, and fixed my tuning issues. I noticed these the second I screwed in a P4 plug and the engine fired. Before, when I had a c6tgc plug in my engine, I was having flame outs and the guys at the track tried to tune it but couldn't. Screwed in the P4, tuned it perfect in 1 minute, got the car back on the track, and it felt different, it was a difference noticeable by me, not a small difference that only a
pro may notice, a big difference.

No power decrease, truck felt faster and felt like I had more torque.

BTW, all the racers I know who run a P5 use a P4 or P3 plug and all run perfect.