I sprayed the car last night and it backfired. One exhaust backfire towards the top of 2nd gear in the upper rpm's. It's a dry shot. The A/F was 13:1 with two #30's. It put about 55hp to the rear wheels. I put in two #32's. Made one pass at the track, didnt hear a backfire. Sprayed it last night and got the backfire. Was'nt real loud, but it bothered me. Should I go back to the #30's? What caused the backfire ?

 

Maybe lean have you ataped the car?

 

I dont have access to Atap. I was thinking it went lean as well. I have no nitrous experiance, I have only sprayed one bottle so far. I think I'll go back to the #30 pills. I did'nt see any real gain at the track anyway. I went 7.27 on the #30's and 7.26 with the #32's.

 

Backfire could also be rich, unburnt fuel, no way of knowing unless you have some sort of scan tool. Was this in between shifts or before your shift point.

 

It was before the shift point.