Big boys with cool toys is probably the largest R/C shop in Mississauga. They have tons of stock of traxxas and hpi parts as well as a wide selection of RTR cars, trucks, helis and boats. Their hours are quite good too.
Unfortunately, their customer service leaves much to be desired. On more than one occasion I've had to exchange/ return parts because the salesperson sold me incompatible components for my truck. If you run R/C you can understand how frustrating it is to go and fix something and then realize you were sold the wrong part. It basically ruins your chances of running that day. Their employees aren't the most pleasant I've encountered in the hobby industry either, they all seem generally annoyed.
At this point I tend to avoid this shop unless I know exactly what I need (down to the part number) and my main LHS (Galaxy Hobby) is closed.