Thanks for bring it up Gus, but the dimensions from the manual is only a reference. b has over 5/8" from the bell mouth and I would say it should be just fine. I have seen 1/2" being cooler running, but perhaps has to do with the design of the pipe. Basically, once set up, you wanna run it on the ground at full throttle and take a look at the temperature. If it doesn't over temp on the ground, it would only get cooler in the air.

Regards,
Barry