What parameters did you change when you played with the tune. It all depends on what you did as far as changes. More info needed. What type of plugs did you put in it?
Go with the 325 they will fit just fine on a 15 x 10 wheel. 295 are just plain too small. I have 295 on the back of my 'ol truck with a 15 x 8 and they still look too skinny.
Yeah I know that Bill guy he does some pretty good work. He has done all of my suspension, exhaust, clutch, gears and intake. Of course it does help that he is my brother too