i was looking on slhondaparts.com and i was wondering what's the difference between teh si mid pipe and the dx/xtd mid pipe #20 in parts pics but the price is different. can sumone tell me. i have a header cat and a exhuast on my dx that's my friend told me was supose to fit his si. and it does but the muffer is being push back to far and when i gave him my stock muffer we could hang it completely. anyone know why?