Ok had a knocking for a while usually while changing gear or applying/lifting off the power. Im sure its the exhaust knocking and I have noticed a few threads mentioning this problem but is there any reason why its happening apart from back exhaust design??? I have an Apexi N1 Titanium and it looks like the rear hanger (not the 2 closest to the rear) is hitting the rear sub frame.

Thanks
Chris

 

just notch out some of the sub frame

 

I just got an Apexi N1 Revolution and also have knocking problems but it came from under the passenger side seat.. usually at low speed and poor road conditions but it is really annoying!
Took it back to the garage and they moved the rubber hangers a little and it cured it for an hour but as soon as I spend some time on some bad road surfaces back comes the noise.
When I looked at the Apexi on the ramps it seems it is a really close fit to the subaru underside chassis.. is it just badly designed from that perspective or can I do something about this... I don`t want to bubble wrap the exhaust and have it catch fire LOL
I`m also in Japan so if I tell my garage to "notch out some of the subframe" will they know what the hell I am on about... In fact if it is coming from near the front passenger seat it may be nothing to do with that..
Just really annoying after spending a lot of money to have this.. it was fine with the Kakimoto exhaust until it broke :-(

I have a MY99 STI if that helps.. anyone had the same issue?