I purchase the Bills SA-4 for a 07 crf450x. It arrived without a mid pipe. It took Bills a week just to ship that. When it arrived I started the install. Come to find out the canister nor mid pipe had the "hooks" for the springs to connect to. Literally there was nothing to hold the canister to the mid pipe. Bills also does not list their contact info on their own website... I returned this product for a pro circuit t4.
Just got this for my Rmz450 by far the best pipe I have ever ran! Very pleased with bills! Would choose it over any other brand I have had (fmf ect)