It is possible to restore the power on post A4 models by replacing the exhausts and the carb tops.

Models A1-A4 produced around 110bhp. This was reduced to a mere 92bhp with the introduction of the A5. Don't believe people who say you won't notice the difference and that the A5 is plenty powerful - it is NOT and you WILL.

The exhaust on early GTRs had a bigger exit hole and produced more power. I believe a Neta exhaust restores most, if not all, of the power lost by the smaller exhaust (but check before buying).

The biggest difference is from the carb tops. These can be purchased from Kawasaki at a staggering £20 each (you need four). Believe me it is £80 well spent!

As the pictures show, the restricted power carb tops have four raised sections which restrict the movement of the carb and thus limit the power.

The unrestricted version from the earlier models are directly interchangeable and do not have the raised section. Make sure you order the tops from an A4 or earlier (I believe the part number you want is 16005-1056).

As for even more power - I believe it is possible to achieve 135bhp or more - the engine used in the GTR is a detuned version of one that was also used in other, more powerful Kawasakis.