I agree with Peter F on the HPE stuff. In fact I ordered the HPE in titanium from M Tec last May. Since then I have received no exhaust and have been billed not once but twice.
Communication has been spotty at best. They claim to have sent something but were never willing to provide tracking numbers or any updates. Needless to say this is now a dispute being worked through American Express.
I cannot recommend strongly enough that if you are looking to purchase the HPE stuff that you do it through someone like Sandbar and
NOT M Tec.