[Nezil]

Originally Posted by 3t3p

Sometimes at low speed in first I try to apply throttle smoothly and the car feathers/see-saws with power forward. Anything to do with the stock valve?

This is at low to no boost however.

Yes, I'd agree that the torque curve isn't totally smooth through the revs, and this is most apparent in lower gears because you feel it more. The tune you have will affect this though. The stock valve shouldn't affect this at all.

The M2 has a stock valve which is already an upgrade over other N55 engines - it's the DV from the N20 I believe. It is made of plastic, but it's not hard material against hard material. There is rubber in there too, and I'm confident that it seals just as well as the upgraded parts, and the manufacturers of those parts will I'm sure agree.

The DV+ has an optional spring which allows it to hold some of the boost where the stock valve would release it all. Without the spring, it's an upgrade in as much as it's less likely to fail being made of machined metal rather than plastic, it's not an upgrade because it seals better.

I know less about the Turbosmart product, but again, I don't believe it will seal any better than stock, but is almost certainly an upgrade in terms of reliability.