I had one installed when my transmission was out for the Suncoast install this past spring. My transmission person highly recommended installing one to increase the line pressures.
Many on this list had recommended the Transgo Kit install as well...
I also have had one installed in my Dodge Cummins with a Suncoast for well over 15 years now without any transmission problems.
From the Transgo Web site:
TRANSGO PART: 45RFE-HD2 CLASSIFICATION: REPROGRAMMING KIT
FITS: Truck-SUV 99-09 3.7L - 4.7L - 5.7L . 45RFE, 545RFE & 68RFE
FEATURES: Corrects/Prevents/Reduces: 2-3 neutral, Drainback, Limp, TCC slide bang and Slip codes. Heavy Duty Accumulator plate/cover and Special accumulator seals. Has tough Snap ring, Saves Pump and VB. Includes new TC limit valve system.
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Supporting Vendor and Moderator of LOST05 Jeep Liberty CRD Limited 
Ironman Springs/Bilstein/Shocks
Yeti StgIV Hot Tune
Week's BatteryTray
No FCV/EGR
Samcos/ProVent
SunCoast/Transgo
Carter Intank-pmp
2mic.Sec.Fuel Filter
Flowmaster/NO CAT
V6Airbox/noVH
GM11 Bld.fan/HDClutch
IronrockArms/wwdieselMount98 Dodge Cummins 24 Valve