[not a gt]

I see this is an ancient thread, but I got mine from SR Customs off ebay, not sure of the hole size (though both holes were the same size). I like it!! It isn't an in your face difference, when I first crank car, rpms drop much quicker, idles steady and smOoth at 800 rpms (notice rpm steady, but shaker is moving more like a cam installed, again subtle). Turned on A/C and headlights, idle dropped to 700 and stayed between 700 and 750 rpms, everything is real smooth and steady. When I bump the throttle to 2-3k and let off, revs drop quicker, but again it isn't massive (reading all the post I think where I got mine the hole size must be conservative), but overall, I like it and for $6.30, a bargain and worth a risk, I brought the original gasket and an 8 mm wrench with me in case I had to swap back, but zero issues, though I only got about 125 miles on 1/2 tank , could be the 4:10 gears and my right foot , don't really see how this could affect gas mileage (????), but in general pretty easy mod that works as advertised, don't find that very often nowadays. My two cents, have a nice evening everyone!!