Ask The Pro - Answers

Straight Pipe Story

By Tim Carrithers, Photography by Honda

Q I just bought a 2009 Honda CBR1000RR and I'm looking to modify the exhaust. I'd like to install a slip-on rather than a full system, but after reviewing the available slip-ons, almost all of their mid-pipes make an S-bend before reaching the end cap. The only system that doesn't is from Two Brothers. I'm no scientist, but wouldn't a freer-flowing straight pipe improve horsepower over a pipe that make several turns?
Pepe Martinez
Royal Palm Beach, FL

A You're on the right track. All things being equal, gas flows more efficiently through a straight section of pipe, but any good exhaust system needs to produce power throughout the rev range, not just on top. According to AMA Technical Director and former Team Honda crew chief Al Ludington, "On a bike with stock head pipes, the diameter of the exhaust tubing is probably way bigger than it really needs to be. The bends don't offer any kind of meaningful restriction. If you were to dyno the straight pipe and the S-pipe back to back, I'd be really surprised if there was a power difference. Usually the S-pipe will package a little better and offer better cornering clearance and access to things like the oil filter and drain plug. Ask yourself how often you use full power when you ride." If the answer is not that often, a slip-on with an S-bend will work fine.

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