Hi, all i'm new to this forum. I have a 90 GT4 Celica, and am currently having a 3 inch mandrel bent exhaust put on it. I purchased the dump pipe, Hi flow cat and muffler on ebay, but the dump pipe i bought had a different flange to the original so have to have that modified.... no big issue, but the guy at the exhaust place reckons there is no room for a cat under my car, and has recommended that he make one up that fits into the dump pipe!!! Just wondering if anyone else has had this done, and what difference did it make???? cheers