Restrictive inlet manifold rubbers - do racers modify?

[stickshift]

When installing my Hordpower intake (and removing the throttle bodies) I was surprised to see that the inlet manifold rubbers' opening was much smaller in diameter than the throttle bodies. I imagine this is for optimal flow to improve low-midrange power and torque.

Has anyone opened these up to a larger diameter? I imagine it would help top end power for the track, I'm sure some racers would have done this but keen to hear your thoughts.

I bought and modified a spare pair that I'm keen to try out on track - pic below comparing a standard rubber (left) to one I modified (right).

 

[mossrider]

Sure do. There's threads about it in racing tab. The value of which has a lot to do with the totality of your mods and tune and what/how you intend to ride. For instance, opening up the exhaust side only gets you so far before you have to open up the intake side before you need to rework the combustion in the middle which necessitates cams which requires a tune which permits...

...Sigh...

Throw them on and see what's what.

[stickshift]

Thanks, suspected as much.