Meh...I had a chipped piston...sh1t, half the skirt was gone...once I changed the plug out of that cylinder...it didn't misfire evah...until it started knocking...literally. But first things first...before you even buy a motor...buy headers...they are $200 brand new off of EBay from Speed Daddy...you probably would have been knock free if he had you down at 4* of knock with headers on that car...also...what was the WOT timing set at? Anything less than stock isn't good for the car...