Matching exhaust manifold to exhaust port?
 

This is probably a dumb question, but is the stock HPI manifold rectangle supposed to be dramatically different than the engine port?

Would performance increase or decrease if I matched these?

I just noticed this after an exhaust leak developed at the gasket interface due to loose screws.

Any help for a newbie to nitro?

Yes. You can use a dremel to enlarge the hole in the manifold. I think it will not be much but it should be noticeable.

Thanks Roelof, This abrubt mismatch seems very restrictive to me so I thought this might be intentional by HPI to prevent over-reving or something like that.

I will give it a try and report back.
Thanks,
Tom