PureStang

This will prolly sound pretty newb but I was wondering what the deal with X pipe are. I have been introduced to them recently and am wondering what they do.
midpipes are cross overs to equalize the back pressure created by the engine

My next question is can I install some type of x pipe (w/o cats) when i already had my magnaflow cat-back exhaust put on? cause the guy that put it on welded them together so would it be possible to have him put the x-pipe in?
yes you can have an x pipe installed....the welding of the catback will not affect the x pipe cause at the end of the catback there is a flange that attatches to the xpipe..and there is also a flange at the header.

Last question is if i had the x-pipe put in, what exactly would it be replacing on my catback exhaust system? Thanks guys!
you will not replace anything on ur catback...you are replacing your mid pipe...stock gt's come w/ 4 cats (or 6 if u have a 94-98 gt) contained on the x/h pipe..replacing w/ an aftermarket mid pipe you will usually reduce ur cats to 2 high flow cats or no cats..u will loose a little bit of low end power due to the less back pressure but you will feel the gain in the top end

you can also get an H pipe if u want...but the x pipe will yeild better results...

there are 3 parts to your exhaust....headers, midpipe (x or h pipe) and catback....

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Brandon J