Why change to an aftermarket exhaust system? Slip on or full system?

Aftermarket exhaust modifications fall into two categories: full systems and slip-ons. The full systems replace the entire stock system including the CAT. High-end exhausts with titanium headers still offer fair weight savings compared to the stock ones. Some headers have various tapers and crossovers to enhance low- and midrange torque while still improving top-end power. In fact, some systems offer minimal gains in peak power, choosing to instead shape the power curve for more midrange and a broader horsepower peak.

However, one possible disadvantage of aftermarket systems is that they require the removal of the servo-controlled valves that some OE exhausts use for better low-end power. Although installation of a full system is a relatively easy modification, many riders choose to mount slip-on systems. These range from simply bolting a canister to the stock S-bend of the header or replac-ing the exhaust from a mid-point back.

Since the system becomes a hybrid of OE and aftermarket components, the power gains are mini-mized. Still, if your bike has a heavy muffler, shaving those few pounds can be the same as adding some horsepower. Also, slip-ons don't require the removal of exhaust control valves such as Yamaha's EXUP system.

SO... Is it all worth it? Do you get power gains with an after market system? I would suggest you do, infact having an after market full system and power commander mapped has given my R1 considerable power gains. I will be getting on the dyno this month and will document the results for RBB

Good post mate...

Wanted to add that many new bikes only use the servo motor in the exhaust to control noise and not low rev performance.

The recent GSX-Rs are a case in point as when you remove the SET valve, you get a nicer exhaust note and no drop in performance (a slight increase).

You must fool the ECU though by cutting a wire, otherwise it will go into failsafe mode and the bike will run quite badly.

On the new R1, I hear Yamaha have finally ditched the EXUP also.