The problem with the Japspeed stuff, is that it's made in China for a very low price, because of this the quality control isn't great. You may get one which fit's pretty well, you may get one which doesn't. As it's already been on a car, I'd presume that if any adjustments (I had to use a club hammer, a vice and a blow torch to get my K2 to fit!) were required they will have already been made.
After about a year or so I get a rattle in the tail pipes, which was the inner sleeve vibrating, I hit the bottom edge a few times with a hammer and it stopped the rattle as it essentially crimped the sleeve in place