alright..about a month ago i got dyno tuned by jeremy formatto and the car made 334rwhp, but the car would miss and jerk eventually into the next gear after the tune..he told me he believed it was spark blowout and recommended i get ngk TR6's and gap them at .35...before i got a chance to do that (about a week later) the car blew a head gasket..so i get the car fixed new valve job and the heads resurfaced..and we put the new TR6 plugs in gapped at .35..i took it down to the dyno today and it made a best of 308rwhp..granted it was pretty hot today..and it was a different dyno (both places dynojet) would there be any other reason for this pretty good chunk of power missing..would the switch from ngk TR55 to TR6 be this huge? or the temp difference?

 

Usually people only run the NGK TR6's with forced induction or nitrous applications - as they are a colder burning plug. These may not be the best plug to use for your application.

I would take a plug or two out and see of they look fouled already. If they do, then you need to move to a hotter burning plug....