worth the cost. It's plain and simple. The advantage of exhaust like you said, can be used on a tt. It also helps with other mods. But you can also get an ECU for $250, and reflashed for $50. So, you pay less initially, and when you convert to the darkside, you get the ECU upgrade for only $50 more keeping it under what you paid for exhaust. The downside is that when you convert to tt, you're going to have to change the exhaust anyway.