I did the CS rear torsion bar first, then the CS intake and cold air duct. Those mods made a HUGE difference. I was happy as a clam right there, but I couldn't stop myself. I really could have stopped there. I went for the CS exhaust mainly because I found a used one for a good price. I LOVE the CS exhaust performance, but I really wish there was a quiet muffler option. Don't get me wrong, it's quiet compared to many exhausts, but since I drive basically 100% city, I'm mostly in the low boom-range (~2000 rpm) of the exhaust and I often find myself wishing it was as quiet as stock. The short shifter is also a must, but you could definitely wait for that as the stock shift setup is already fantastic imho.