If you think adding an exhaust will make the faster and more powerful, you're wrong, maybe a tiny fraction but not anything huge. If you just want it louder then go for it.
It won't take power away from the engine though. Just put one muffler and a rear resonator on, quite common.
-Democracy must be something more than two wolves and a sheep voting on what to have for dinner.
James Bovard, Civil Libertarian (1994)
-Giving money and power to government is like giving whiskey and car keys to teenage boys.
P.J. O'Rourke, Civil Libertarian
-Government's view of the economy could be summed up in a few short Phrases: If it moves, tax it. If it keeps moving, regulate it. And if it stops moving, subsidize it.
Ronald Reagan (1986)