Originally Posted by
James @ M Developments.
If you are using a big turbocharger you will need to rev it to get the full potential so double springs are a very good idea
If you run the BD16 or BD16+ inlet with double springs is it fine to run the exhaust side with standard springs.
Also is the only difference between Newman springs and ISKY the diameter of the spring? i take it for ISKY you remove the standard valve spring seat and machine a seat within the head?