Yours 370 HP vs 6-speed 376 HP. Rear gears will mean more with the 6-speed. I think Dodge has under estimated the HP to keep it below the SRT-8s 425 HP. Seems to me R/T is closer to 400 HP and a $10,000 difference in SRT and R/T. There are some easy mods (bolt ons) and some not so easy intenal. Chip,Exhaust and open element intake are the first and easiest. Then comes a lot of expensive and more mechanically challenging parts. NOS, blowers, and turbos. Cams, heads and intake manifolds. Ect. Ect. Look to Mopar performance parts or after market support. Also check E-Bay Motors.