H HISS GT Founding Member Aug 8, 2001 104 0 0 Norfolk, VA Apr 2, 2006 #1 Apr 2, 2006 #1 Are all 4.0 heads the same and interchangable? Are there any documented gains from port and polished 4.0 heads?
Are all 4.0 heads the same and interchangable? Are there any documented gains from port and polished 4.0 heads?
