If cost is an issue for the TB's - This dude is making some pretty good manifolds -

http://www.ebay.co.uk/usr/dansteng

and I've also heard that these guys make some pretty amazing kits for caterhams/lotus 7's etc -

http://www.boggbros.co.uk/fabrication.html

but haven't had any experience with either. (I had mine fabbed locally)

cheers
Lach