ok so i have a 01 GS-R and when i bought it had a grddy cat back, 2.25 inch piping i believe, i measued and thats what it came to aprox, well anyway, too loud for my taste, so anyone selling their ITR axle back since that will fit mine fine and it is also 2.225 piping,wont make a bit of diff other than sound so just let me know, thanks. also if you know a great website that sells parts like that or something that would be even better, thank you.