[IanRTL]

There is almost no specific aftermarket performance support for the RL. There are many who have done some great things with the J-series engines, but it's a lot of custom work. The 3.5 liter engine can handle a lot of punishment, but, as was said, the other drivetrain components cannot. The transmission and rear diff unit are designed to handle 300lb/ft of torque max. That doesn't leave a whole lot of room for improvement before you severely hinder the reliability of these expensive parts. The reason the new 2nd gen RL will have a different transmission and rear diff unit is to increase fuel efficiency and handle the extra power delivered by the direct injected 3.5 liter engine. If you're looking to mod a truck for performance, you've chosen the worst candidate imaginable.