Mate the varex systems are way too loud when open and so restrictive when closed. These engines have such loud low rev engine sound and its hard to make an exhaust that is not loud.
Ive had aa apex-n1, straight through with varex, fujitsubo legalis r and now a kakimoto hypermega and have to say that the fujitubusu legalis is the quietest followed closely by the kakimoto hypermega n1. If you can get your hands on either of these systems you will be more than happy.
Loudest system ive had is the apex-i N1. This thing can be heard from like 4 streets away.... stupid loud