Stealth tuning

What is to gain from tuning a completely stock motorcycle?

I can understand that not everyone wants to make a lot of noise and risk being pulled up by the police every 5 minutes. Getting done for noise, followed by the hassle of rectifying the defect & organizing a road worthy certificate – what a hassle right? Besides all that, stealth mode does have some advantages, and it does not cost anywhere near as much to concentrate on improving what you already have.

But back to that question, can we improve on what is already there, make the bike run smoother, and produce more rider friendly power without drawing unwanted attention? The answer is most definitely YES. When the manufacturers eventually sort out how to produce bikes that comply with Euro 5 (which now is looking like being delayed for 12 months), there will be even more that can be improved.

Here’s a few things that can be done right now. Every bike has an exhaust valve – its job is to reduce noise. If the bike revs to 10,000 rpm the valve will not be fully open under 5000 rpm in most cases. We can open it early which improves throttle response and acceleration. Most stock air filters, and intake systems are deliberately designed to reduce noise. Replacing the air filter with a DNA substitute improves air flow. The same is true of airbox, designed to reduce induction noise and often this will also restrict air flow. Removing the rubber snorkels and/or cutting a larger hole combined with some clever tuning – increases throttle response and power right through the rev range.


Very few motorcycles now are free from ECU restrictions. Your bike may have secondary throttle plates that never fully open. Or if the throttle valve is controlled electronically there’s a high probability the throttle map is conservative even in sports and race mode. In some cases, the throttle valves start to close down as the rev’s build closer to redline even though you are holding the twistgrip steady or fully open.

Therefore, there is plenty to do and improve, without making any expensive exhaust upgrades, all the while remaining in stealth mode and free from police and EPA harassment.

There is something kind of cool about that don’t you think?

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Marcus George
Marcus George
1 year ago


Hi Dave,
Can you de-restrict the Triumph 660’s?
I’ve been told that this is done by the dealerships in the UK to unleash its potential 94 hp, just can’t find anyone who can in Melbourne. I like the stock exhaust note, just want the full power.
I know you do it with the CBR650R/CB650R, I just prefer the standard exhaust note from the new Street Triple 660’s.
Any advice and guidance (Costs) will be greatly appreciated.