With the OEM chip the car actually runs its best. The only problem is that with the upgrades I have done (i.e., cam, pistons, etc.) the rev limit is to low and I am missing out on some high end power. The P75 chips I got would take it to 8000 rpm, but the problem came along with it. As far as the detonation, I'm only guesssing as I have only read about what detonation is. It almost fells as if one of the cylinders doesn't fire but its not constant. It is random. My other guess is that the mapping for the P75 chip has different timing setpoints than what the PR4 does. You say they are the same but why did Honda label them differently if they are the same. There has to be differences. Any other ideas?