To my knowledge it's 56mm.
As for the swap, was pretty straight forward IMO. Pulled the TB w/sensors attached for $30 from my local U-Wrench-It.
Worth it for the price in my case.
I did the swap... I think its too much of a low end loss and doesnt really pull as hard before redline. If the redline was lets say 6600-6800 mabey it might be better but from my experiance its not worth the loss. It seems to start to pull later than the stock 52mm
i did it , worth it if you ask me, causes a major change in your powerband though,
If you can get a 95. it is the easiest swap.
PRND321 Till I DIE
Old Motor: 160whp & 152ft/lbs, 1/4 Mile 15.4 @88.2
M45 + LD9 + 4T40-E, GO GO GO
I bought a 2.4 mm tb that had been bored out to 56mm for 150 dollars. It was very easy to install. I did feel a litle gain. If I had it to do all over again I would have spent the money on a B&M short throw shifter. I would have bought a bigger throttle body eventually because I was going boosted, although I would have looked for someone selling a used RSM 62mm tb. The only problem is everyone wants one of those. The last one I saw used on ebay went for I think around 250 dollars. If you do not have a boosted car I would put the money into something else.

FORGET GIRLS GONE WILD WE HAVE GOVERNMENT SPENDING GONE WILD!