I 100% agree with them. I did 4.10's first, which required a tuner to correct the speedo, so then I did the CAI more recently. As my car is an automatic, I also did a big stall converter to launch hard like a stick shift car instead of mushy like an automatic.
Just a little more and do Gears / CAI and tuner.....after just those two mods, youll think youre driving a totally differnt car. Im gettign 3:90's since im on the freeway alot. I just did roush pulleys and CAI with tune and WOW for an automatic it kick me in my seat. No more throttle lag, istant repsonse !