We need to differentiate between canister, and pipe....compared to what you now have. In the picture you have a fairly 'OEM' restrictive exhaust. Certainly a canister or tuned pipe setup would GREATLY increase the power of your homelite. To my knowledge, boat racers don't run canisters, but rather tuned exhaust headers with pipes. If you aren't going to go with a canister or tuned pipe setup, letting whatever 'other' muffler option you consider breathe is the best you can do. Empty the guts out of that OEM can, or find out who's running what aftermarket muffler on that engine and go with that....etc. Restricting the flow on an OEM style muffler won't do any good. Try running it without the muffler at all, and compare the performance. That will give you a baseline, and you'll know what your muffler is doing to the performance.

Chad