Wow just seen all this. Ross bieng his typical self in that his way is the only way everyone else is wrong.
At the end of the day its down to personal preference, how you want the car to act and sound. There are way to many variables to simply say no DV-loads of lag, DV-no lag... I'd be much more bothered about the spec/build/map of the engine.
BUT what i can't stand is people banging on about it damaging your turbo, none of the big power cars round here run dump valves, I don't my mates 500bhp+ astra doesn't, a 700bhp scooby doesn't... All without problem. The internet breeds rumours like this and everyone gets scared.
