Fairly good bang for the $$$ 2004 Pontiac GTO
If you want a cheap way to add more power, the cortex is the way to go. I have an A4 "automatic" and it still breaks loose in 2nd gear. Spinning the tires at 40 mph. The gear changes are faster and more smooth, it adds a lot of torque. Overall a good value. The only downside is that there's not many options on there tune for add ons. The only thing the tune covers is a cold air intake. It doesn't have options for headers w/ high flow cats, or a catback system.