Alright, well blackhat mentioned a expansion tank for aerox on my intro thread which increased his mates top speed, question iss... What is a expansion tank? What does it do and where does it go?

BH said "Expansion pipe", this is an after market exhaust. Normally giving better performance.

Not to be confused with an expansion tank, which is a water overflow container.

Awwwwwww understood now I really should read things twice cheers

No worries.