Does Ecv Make Restriction>?

[gt-t_r34]

hey guys im just about to do the front half of my exhaust with a BATMBL split front and dump and some sort of high flow cat(reccommend if you like!) i also want to put one of those Apexi Exhaust Control Valves on so things arent so loud so i will have 3inch front to 3 inch cat the 3inch blitz cat back ive just found out that the 3" ECV 80mm isnt actually a flange its a pipe and i dont want to have to cut the cat and cat back up to weld it in... so the only other flange type is the 67mm(nissan one 155-A014)which is 2 3/4" i think would the smaller flange piece be much of a restriction when fully open doesnt matter when closed! ive posted pics of both and this is the link to nengun so tell me what you guys reckon.

http://www.nengun.com/catalogue/product/239

cheers simon