Well not necessarily a BIG no, lets consider the benefits. Cobra Crazee may be onto something for his application. When the fuel/air is not so likely to detonate (higher octane or perhaps water/alky injection) you can run more 'boost' or a higher compression ratio and get away with it. Simply doing that will make more horse power. Also you can run more advance in your ignition timing, which is almost always a good thing. So there ARE potential benefits when used wisely, correctly and carefully. The real question is: Is it worth the expense and hassle? Do the benefits out weigh the risk? With a German fighter pilot on your tail and your in your P-51 Mustang you need ALL the power you can get right NOW! To heck with damaging the engine, you gotta survive the dog fight first!
When you MUST win at all costs, perhaps it's worth investigating.