My two cents !!!
Like everyone else, my 85 windows (Doors & Endgate) ran slow compared to todays window speed.
In my resotraton, I relpaced the motors, regulators, felt, in the doors and in the endgate, the regulator, drive cable, and felt and left the motor aloone.
They were even slower after the replacement and i used silicon lube in the felt tracks and also a special Honda Window Lube grease I found out about on the internet searches.
I decided to go with the relays after much consideration.
I looked at the LMC Kits as well as building my own.
I found the K5 Squared Full Power Relay Kits that contained both the doors and the Endgate.
I went with this package due to cost for the package versus purchasing the doors then deciding to add the engate.
Full Power $125.00
Doors only $100.00
Endgate only $95.00
Installation is super easy once you see enough videos and follow the instructions. The only issue I really had was running the Power Line from the battery down the frame to the endgate utiliizing the existing wiring loom. It was tight and a challange, but I was able to get it done.
I am fully satisfied in the results of the added relays.
I did the doors one weekend as I was working on the interior and had not put the door panels back on at that time.
I installed the endgate relay the next weekend and it took a couple of hours only because of wanting to use the wiring loom and not just zip tying the power lead to the exisitng loom and wiring.
Wiring harness that will help the speed of power windows in K5 Blazer, and Jimmy. Wires, fuses, relays, mounting hardware, and connectors are all included to complete this upgrade on your K5. **ALL KITS ARE MADE TO ORDER, SHIPMENT MAY BE DELAYED A FEW DAYS**
k5squared.com
To sum it up .. I am extremely happy with the end results...
Good Luck