Powerflow Exhaust

  1. Newbie Joined: May 2011 Posts: 20
    #1
    I have just bought a powerflow exhaust, i have seen on here that a 4" backbox on hear is not verry good with performance, although my backbox starts like a standard backbox goes to about 2/3" then the bit that shows at the back is about 4" will this increace or decreace performance ? thanks.