200R4 update
The Wilcap is nice, but it's more than that. I am also swapping to a 2004R and ordered the Wilcap kit. The $550 is for a neutral balance kit, but they charge $100 extra to build flex plate for an external balance 360.
It may be a little more money, but it looks a bunch nicer than a flat, square piece of aluminum. Looks like it's worth every penny. Looks like this type runs $550 here:
http://www.riley-auto.com/ADAPTERS.html
And the TCI is $471.38 here:
http://www.race-mart.com/TCI-TCI-149160.html
I think the Wilcap is $80 nicer.
The Wilcap is nice, but it's more than that. I am also swapping to a 2004R and ordered the Wilcap kit. The $550 is for a neutral balance kit, but they charge $100 extra to build flex plate for an external balance 360.