never really proved it... it seems worse some times than others? even at the same rpm/load? weird..

Been looking into changing the N75 valve and apparently this is fine for remapped cars.

The J version supposedly builds up boost quicker and holds it for longer.

The H version is more prone to surging.

Alot of the Seat peeps have this done with no problems.

Although my CAI has improved low down response I feel it could be better still. I wonder whether changing the N75 would help seeing as it build boost quicker.

Anyone got any ideas?

Cheers.

Adrian.

Yep, surge happens because the spring in the wastegate is too fast for the ECU to control properly. It's too fast because it's too weak. You can't change the spring, so bleeding some boost from the line that goes to the N75 will do the trick. Less boost going to the wastegate means it'll work slower, and the ECU can control it easier. Modded or chipped cars tend to surge because the added boost increases the speed of the wastegate spring.

Regarding that turbo, it's bigger than a GT30. I really don't know about tubular manifolds though. I'd prefer a cast one.

Speedy G