Quote Originally Posted by fst View Post
he's still on stock 3.8" (mps) pulley. never had an issue until recently. i'm the one that has been tuning it for him. his spark timing at cruising is mainly stock. he still has the u-bend on there. Wizair intake. he doenst recall the plug type. he just recently started getting this. his tune has mainly been unchanged for nearly year now minus at WOT.

edit-one idea for now would be lower the timing where he's getting KR or richen the hz range where its occurring until he gets more exhaust mods.
If you are still tuning, and its definitely only happing when heatsoaked, check out the IAT temps and use the IAT/spark table to pull a couple degrees at those temps.