CONVERTOR SIZE?
 

Can someone tell me the benefits or drawbacks from a smaller 8in compared to a 10in convertor?

No drawback to either, each has it's place. A 10" can stall about 3500 to around 6000 depending on the engine, an 8" from about 5000 to over 7000 ( I have an 8" that stalls 7100). Vehicle weight, engine torque HP and RPM range, gear, tire size and trans type all play into the right one. Let me know what you plan to do with it and I can steer you in the right direction.

I was told by a manufacture that my 9.5 don't have the effeciency as a smaller converter. He recommended an 8" Converter.
Maybe it was a sales thing? maybe he know what he was talking about?..

I would call Coan or another good converter manufacturer and tell them everything about your application and have one built to your needs.

What he said, depends on combo mostly.