I agree, given the drop in quality of the newer stillen exhausts and the issues with compatibility with HFCs i find after my experience i cannot recommend the newer Stillen exhausts and in hindsight would have gone for something else.
I have also noticed it has started to rust, despite the fact that its only 3-4 months old and i clean it regularly. Stillen exhausts are definitely not what they used to be.
However it does sounds fantastic.