If the muffler has internal insulation (vs. just steel baffles), it may have partially collapsed, blocking too much exhaust at higher rpms and forcing it out before the muffler.


HUMMER .25: No need to compensate.

1989 Dodge Raider: 3.0/5
1992 Chrysler LeBaron Convertible: 3.0/A
1994 GMC Safari: 4.3/A