Cadillac CTS-V - Throttle Body Coupler

I have the Nick Williams 102 TB (not installed yet) and it says it has a 4.23" OD and I'll want a 4.25 coupler.

I have a Volant Air intake tube which I'd like to keep, and am not sure the OD on the stock LS6 TB.

Does anyone know what size coupler/adapter I'll need? 4.25 on one side.....____ on the other? Also, where do I find one of these?

http://www.siliconeintakes.com/index.php?cPath=2&osCsid=a550e950893407e1c860213a0382a60d

Don't see 4.25 though...

Here are some options that start at 4.25" and can go to a 4" tube:

http://www.racepartsolutions.com/products.asp?cat=26

Thanks fellas!!!

Does anyone know what OD I'll need on the other side?