I agree w/ agil. , An aftermarket pipe alone will be disappointing. You are getting the advantage of increased air flow out, With no improvement in. If you run a larger carb./jet, and air filter the improvement is worth the money. As agil. said the main difference is in the diameter of the "manifold" pipe. Increase the size; increase the flow. Take a close look inside the manifold end of your current pipe. Many have a "reducer" welded inside, and this can easily be removed for free,vs. the price of a new pipe. A general rule of thumb is; A thinner pipe will produce better bottom end torque, and a larger will produce better top end. 4t's are very sensitive to exhaust flow. Cam timing also comes into play here using overlap/ duration to adjust for the power band you want. Bottom line is you should PLAN the exact operating range, and use the appropriate pipe. Fine tuning can be done in the cvt to compensate for the shortfalls of the power band of the engine
