I have talked with Gary Sumek at Lenco Racing over several weeks.
They can now offer a permanent overdrive to the back end of a Lenco CS2 racing system. The unit runs about $2600.
It comes between 1:1.56 and 1:1.31 overdrive.
The 1:1.56 overdrive is a 0.64 ratio this would really help a landspeed racer or high speed drag racer at the top end.
Call me if you have any questions, I have already asked him a lot of them.
It is a non-standard part and he will try to sell you a transwarp motor adapter plate and a full system as well. It is basically the reverse of the underdrive "gear reducer" they sell.
He would only put it on the back of a Lenco CS2 without paying for full development costs. So it is a little bit of a big gulp to take. But if you are into building custom plates and shafts this could be for you.