Probably down to preference i'd say, I used to have a magnex when i bought my car, but changed over to a mongoose which i like better. Reason being i think it sounds nicer and i wanted a bigger exhaust( poinless i know) but also there were less boxes and therefore less restrictive. Although the Magnex i found to be better finished overall, nice mirror effect on the backbox. And also if i remember correctly, not all exhausts are made the same way, i.e if you just bend it on a mandrell you decrease the i.d of the exhaust, and i believe some of the more expensive exhausts are manufactured in such a way that the exhaust is the same I.d all the way through??? Anyone feel free to add to this!