Anyone know a good Lawn mower engine rebuilder?

[Randy]

Ok i have two Murray lawn mowers and figured id want to have one of the motors rebuilt as it seems to have lost some of its power.... anyone know of a good place to have it rebuilt? Im also looking to mod it a little with a better carb, intake and exhaust....... i know overkill but wanted to see if i can get some power out of it.

Thanks in Advance
Randy