Downpipe knock?

[DEATH4]

I have the ATR(Houston style)Downpipe and have noticed some of you with the larger DP get knock from it hitting the frame and such. When you say you fix the downpipe and stop the knock what exactly do you do to stop the DP from hitting? I think I have this problem because I get knock between 1,000 and 2,500rpm under regular driving. Then when I bring the rpms up(3,000+) and build boost the knock is gone. The Fel-pro says the car isn't lean or rich. I never get any knock under boost, just when the car is going up a hill or from a stop and the engine is torquing in that low rpm. Motor mounts are fine, fuel is fine. This does happen inconsistantly too. That is why I think the DP is hitting. It is real close to the frame.

 

[salvageV6]

I believe the fix for hitting low would be passenger side motor mount, perhaps the poly. or else the control arm bushings.

Mine was hitting high so I got the drivers poly. mount and cut the bottom off the heat shield. Still have to grind down the body seam mine is less than 1/4" away from that. It has to go....
Mine is a real THDP, don't think that matters much....

 

[Phatman]

Same here....ploy mounts did the trick, I replaced both.