Yank the air silencer. (free)
K&N filter ($40)

Not sure if it applies to the 99+ as I havent looked at a 99+ v6 maf but I removed the MAF post from my 98. Gave a nice seat o the pants feel. Felt like it revved a bit quicker and helped torque out a bit. (2 hrs w/ a dremel tool TOPS -- )

underdrive pullies (steeda sells a set)