It won't be a huge restriction but you will gain some midrange and high end power from a better flowing manifold. I like the Skunk2/Blox design but the ITR will work just as well on your setup. I'm running the stock throttle body, so I won't be much help in that area.

 

AHh ok thanks, ive just been having a look for a manifold and found this
http://cgi.ebay.com/ebaymotors/OBX-I...spagenameZWD2V

What are obx like these days? quality wise?

Would a 70mm t/b be far too big for my set-up does anyone know?

 

Since the opening on the manifold is 66mm, 70mm is too big.

I still won't trust OBX stuff. It'll probably work fine but for the same price, you can get a Blox.

 

Im going to have the manifold machineed to 70mm to match the t/b,
i got a skunk2 intake manifold on its way as well as a 70mm skunk2 t/b.

Ill soon see what differance it makes.