I was wondering if there is a smooth rubber coupling for a stock ls1 throttle body between maf and throttle body? The stock rubber is like an accordion and seems to be restrictive. I thought, at one time, I saw a smooth straight coupling. any helps thanks.

 

SLP makes a good one, it's not cheap. They call it " Smooth Bellow" #23065

 

Or you could do the fernco mod just go to home depot and save you some money paid 5 bucks for mine

 

Fernco is probably the best bang for the buck bet.

Although, it looks like you spent $5.
I want to change mine (I use the same stock one as you're describing) but I really prefer the OEM look. Haven't really found anything that looks better yet.

 

Not to rip the thread, but what if I'm tuned speed density

 

The stock bellowed coupling is not restrictive (the bellows just bunch up, air just flows past them)... also, it allows the engine to move easier without breaking your lid.