Any of the canisters will increase power increase available torque - OR allow more rpm
the setup is what makes the difference
homemade canisters can and do increase torque and done properly will raise the max torque and the rpm at which that occurrs
some are intended for the "bolt in on and hope" guys
but-what works at one rpm may not work at another .
in a nutshell
to increase power -you must BURN more fuel- and a decent canister will allow really good exhaust flow without causing "out of sync" pulses back into the engine
which are best?
I like the old JMB- pretty tolerant of header length
not any real boost over open exhaust but a nice quiet tone
I don't like noisy engines
tuned cans ?
YOU have to set the right length for the rpm.
And that depends on the prop load