[ob_1jr]

Ditching the cat will lower EGTs. Your truck might throw codes, but there are parts to get rid of those. FWIW, I have a 4" mbrp turbo back (offroad kit) and it has a noticable drone while driving. I think that my truck was quieter when it was straight piped....at least if I kept it under 2200 rpms. For the CAI, I would either go with the AFE with the proguard 7 or I have heard good things about the S&B intake too. I didn't gain hardly any mileage doing the exhaust and intake mod. Your best bet is to buy a programmer like the predator or PPE for mileage. The predator can be had for around $299 and the PPE is a little higher for the economy one and it can be upgraded for more power at a later date if you decide you want more. The ultimate programming would be EFI Live. You might like that if you like to tinker with settings and work on your own tune.