[pciley]

Without the muffler, of course you would lose power. You need a bit of back pressure for the low end. If you had a supercharger or turbo setup, I could see having dumps or something, but ONLY if you were going to spend all your time near redline. Otherwise you are just hurting yourself.
If you are making the Titan into an NHRA drag truck, maybe go with open pipes. For daily driving, performance would only suffer.