I was looking at potentially upgrading from cosworth M2's to GSC S2's or S3's. I don't think the S2's would really benefit much but the S3's seem like they would really free up the turbo in the rev range.

Things I am worried about with S3's are the drivability and idle, car is mainly a very fun DD and would be used as such (I do like to boost and row through the gears though). Would the S3's or even S2's be worth switching out?

Turbo on the car GTX3582R.

 

You'll benefit from the S3's Mid-Upper range. Yes, it's worth the change.

Drivability and idling will not be compromised either. They do have a slight lope to them, but I don't find them much of an unbearable annoyance.

 

S3s would pair well with your turbo