Probably around 400 to the wheels give or take
its more of a whole combo that you'll want to look at. A Big Bore TB with stock intake, will suck more than it can receive, with teh stock air box being so restrictive.
You get a Big Bore TB Intake, then you gotta look at the Exhaust side, you cant suck in more than you can exhale.
Gettnig a Cat Back helps, but then you stuck with the restrictive Exhaust Manafold, and Cat (or cats if you have a 3rd gen)
Jon has a complete intake done when i went for a ride in his car, and i was hoenstly impressed with teh pickup he had, this was before his complete exhaust went in, So just doing the intake will have its benifits, However, the best solution to free up the HP would be comlpete intake and exhaust..
P.S. i know i didnt give you a HP number, that it because anyone who gives a number will just be an estimate, because i doubt anyone will spend the money to Dyno a car with and without a BigBore TB, unless of course your the manufactuer?
I asume you woudl feel teh difefrent in the top end more too woudlnt you?? Anyone??