Will a larger throttle body such as a 70mm or 74mm be compatible with the K&N FIPK. Theoretically I should seem some gains right?

 

If it's bored out of the stock TB, then you'll be fine with fitting an aftermarket intake.

Your question is somewhat vague and you need to provide additional information, but assuming you're naturally aspirated and untuned, you'll have better throttle response as the bigger diameter will accommodate larger volume of air. You won't see any "gains" beyond that until you tweak the timing and add additional mods. I have a J's Racing 70MM TB which I may be putting up for sale. PM me if you're interested.

 

Yes, I am on the NA route with a few bolt ons. Thanks for the quick response

 

The bored stock throttle's outer diameter will stay the same, so you are fine.

Here's a link with photos:
http://www.scienceofspeed.com/products/exh..._throttle_body/

regards,
-- Chris