MSD's are a great ignition system. You don't need to go overboard on keeping them cool, you just have to make sure they can get some air. Don't put them in a glove box, or way up under the dash. Firewalls and inner fenders are always good bets. If you need to mount it closer than a couple inches from a header, simply make an L-shaped sheetmetal heat shield to block the radiant heat. I've been using the same MSD 6al box on dirt late model race cars for over 10 years... they can take abuse.