Can't get the rubber coupling on 75mm throttle body

I had the same problem, i went to home depot and found a rubber coupling that is adjustable, its got a big metal band across the whole thing that you can tighten further down on one side than the other to make it fit
 
Autozone has all sorts of couplers, and they aren't expensive...

I had 0 problems getting my stock air tube onto the 75mm with spit and spin tecnique, when I got my C&L pipe it came with some couplers, but they were a tad too small. IIRC I got the couplers from Autozone under 10 bucks.
 
Autozone has all sorts of couplers, and they aren't expensive...

I had 0 problems getting my stock air tube onto the 75mm with spit and spin tecnique, when I got my C&L pipe it came with some couplers, but they were a tad too small. IIRC I got the couplers from Autozone under 10 bucks.

It's not the stock air tube. It's the rubber coupling that comes with a vortech blower to connect the discharge tube to the throttle body. Just a 3 inch rubber hose with two hose clamps.