Steve,
When you say custom top, do you mean raised top to bolt to stock tubes, or a completely custom top that will bolt up to a customer piping system with intercooler?
There is more than 1 frount mount system now abailable, one that uses a stock or raised top like normal, which is the Magnum Powers set-up, and there is one with a custom top that is set-up differently, made by Chris Lazzo.
Email me if you need some more info, I have looked into this already.