I'm not sure my car is producing all the power it should be, as the title says it's a 150 brake engine. It doesn't seem to be all that fast, the engine revs freely enough but just seems a little flat. My mate's astra with the same engine is a rocket in comparison, any ideas what could be wrong? I also can hear a faint whistle from the turbo as it spins up, I've had a look and checked for split hoses etc but can't see any thing obvious.