i did it for the same reason as others....scratched and dented and it turned out great. if you want something that sounds amazingly loud chop the muffler in half and take the packing out....
on 93 octane k&n air filter and shorty pipe people could here me 10 miles away at night (2 am) and a cool added benefit is it pops blue flame once and a while

 

yeha i was planning on using a 99-01 R6 stock exhaust because they got the rivets. F4i dont have it, its welded....so im wondering how you guysget it back together after? ps im talking about stock exhaust

 

FMF makes a shorty stunt exhaust for the F4i. it's Ti though and is pretty expensive

 

forgot to mention...my pipe was a Ti FMF that i cut and re-riveted not a stock
for stock i would say, find a really good welder