<font size="2" color="#00265e">SpinnerRow</font>
You can use a longer header to use a 60 size pipe (especially one that isn't 'peaky') on a 90. Or make a moussecan type pipe for similar results, less weight and expense. You might try something like a 12~12 APC on a piped ST90 for around 11,000rpm if you want some speed.
Terry in LP