Actually can someone confirm this? I know for sure the UT Y-pipe is direct bolt on but some of the other y pipes need to be welded ex.: Fujitsbo?

 

To my knowledge, all the discussed Y-pipes are bolt-on to the stock exhaust, meaning the bolt holes in the flanges line up. However, many of the Y-pipe designs (Fuji is one of them) have a larger output diameter than the OEM, as they are generally intended to be mated to an aftermarket exhaust of equally increased diameter. The concern is not that the mis-match would leak, but rather offset to an extent the flow improvement obtained by the smoother bends and 2-to-1 design of the Y-pipe. The sudden reduction in pipe cross-section entering the mid-pipe has an adverse effect at any flow rate. How significant? Well, given the minor gains to be had from a Y-pipe, why give any back? What some have done to avoid this while retaining the OEM exhaust is to add a reducer cone to the beginning of the mid-pipe. In order to do this, the mid-pipe must be cut and the reducer cone with new flange is welded in place making the Y-pipe still a bolt-on. If you have no future plans on an exhaust upgrade, I suggest an OEM matching diameter.

 

Very good advice Mac! I always thought it was a plug and play type deal where not much thought it put into it