Hi all.


Im building a different air filter set up because im not happy with my current one. i checked that my TBs are 45mm so got some 45mm id tube. Problem being that when sizing it up i have noticed that the actual front opening of the tb is bigger at about 50mm.

Will this reduction in dia actually choke the engine? If the butterfly dia is 45mm im thinking should be ok. just want to check.

i will make sure its super smooth inside so the transition between the sizes is nice. The tube will also be at an angle so will be ok in width but not in height.

any feedback and comments welcome

It will make a tiny minor difference, but not enough for you to notice without a dyno and repeated runs with each.