Going red on the outside and keeping the red interior is just too much red, but if you go a dark colour on the outside then the red interior will stand out alot more and it will make more of an impact to people who see it for the first time. Some great colours which would look great with a red interior are: Navy blue, Midnight purple or black.
It's all about what you want tho, there's no point in doing something to your car if you don't like it, after all, it is your car.