I think most have the adjustable PM3....I do. Ability to adjust HP level to my load and driving conditions is a big plus for me. At gross wt, or towing ... I'm fine in TX & OK at full HP.... but going over the Divide in Colorado at gross wt would be serious EGT problems!

You can always add the adjustment control later if you find you need it. PM#2 is the same box... just comes pre set at the level you order.

RJ