revo will do you 210bhp (+/- 10%) from a k03(s) based engine (150/180)
other companies can give you about the same increase too. Jabba, Stealth, etc.
Jabba can give you a bespoke map which will take into account a better air filter and exhaust package where as revo is a standard code for every engine.
you'll looking at about £500 for a remap.