HEADER LEAK FROM HELL!!! please help.

[LOCASH]

Has anyone had any problems w/MAC headers? I have the headers and the H-pipe. There is a leak on the driver side on the rear most pipe. I have replaced the gaskets with Earls and the back pipe is still leaking. I loosened up the h-pipe and tightened it again.....still leaking. Am I going to have to take the whole system apart to fix it? Should I try different gaskets? Please help I know this sounds like a stupid problem but it is making me F****** crazy.

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86 GT T-tops, AOD, B&M shift kit and hammer shifter, ROH wheels, K&N, Timing,MAC headers, 2.5 off road H, 2.5 American Thunder, 87 spindles, rear disc,SS lines, BBK 1.5, poly bushings, Steeda G-trac and subs, Strut bar.
"DRIVE LIKE YOU STOLE IT!"