I've not done it myself, but having had lengthy chats with Glen, power from an ABF doesn't come cheap. You're looking at thousands to crack the 200hp barrier.
How did you figure yours has 165hp? If it's standard you'll be looking at around 150-155 max. To give you an idea on power figures, a worked head with a decent intake setup and a worked TB will see you about 170hp. Cams will add about 10hp depending on which ones you go for. You'll want to have a good fuel map made for your setup, so you're looking at a custom map too.
You'll be looking at about £1500 at least just for 185ish hp. After that it's all about throttle bodies, serious headwork and wild cams which will cost you well over £2000 for the lot. Only then you'll barely graze 200hp. Glen's made 200hp but on a setup that wasn't drivable in the road. I think he's currently at 195hp with a setup for the road. I think he's looking at MS and at a 8 injector ITB setup with some crazy cams that will crack the 200hp easily, however as a road car it'll be almost impossible to live with.
Power doesn't come cheap sadly, it's not like you can stick a £20 ebay flux capacitor that adds instant 45hp
And you're talking about a supercharger too. That'll double the cost of modifying with the charger itself, pipework, manufacturing costs, engine internals, engine management, etc.
You're spending a hell of a lot of money. If money was no issue then great do it! But if it was me I'd rather buy something faster from factory or look at possibly dropping a 1.8T in there. Remap, some exhaust work and a few other bits and bobs (all under £1000) and you'll be around the same power as you would be with a very heavily modified ABF, at a fraction of the cost.
