Ultimate Belts adds five new belts, all of which are faster that what is currently available. The slowest being twice as fast as express belts, and the fastest being six times as fast as express belts. While this can be used with Bob's or anyone else's mods, I have not added special support for other mods. I plan to add support eventually. I also plan to fix the belt animations not always matching their actual speed (stroboscopic effect).

A little more information on what Ultimate Belts adds with base game & Bob's Logistics for reference:

Base Game

Yellow belt speed:    900 items/minute, underground belt max distance: 5
Fast belt speed:   1,800 items/minute, underground belt max distance: 7
Express belt speed: 2,700 items/minute, underground belt max distance: 9

Bob's Logistics

Green:  3,600 items/minute, underground belt max distance: 20
Purple: 4,500 items/minute, underground belt max distance: 25

Ultimate Belts

Green:    5,400 items/minute, underground belt max distance: 30
Red:        8,100 items/minute, underground belt max distance: 35
Purple: 10,800 items/minute, underground belt max distance: 40
Blue:     13,500 items/minute, underground belt max distance: 45
Cyan:    16,200 items/minute, underground belt max distance: 50

During my testing in 0.17 I found that faster belts are possible but belts start randomly decompressing, most noticeably around corners. So, I have no plans to add faster belts. Also, since the creation of this mod, other mods that also increase belt throughput have been created such as deadlocks stacking beltboxes. Special thanks to shanemadden for adding the required code to my mod in order to support deadlocks stacking beltboxes.

These mods have added support for Ultimate Belts (thank their authors!):
Mini Loaders
Replicating Belts

Ultimate Belts can be used with the mods listed below, but I would still like to add better support for these eventually:
Loader Redux
Belt Sorter
Automatic Belt Planner
Bob's Mod's (Current recipes only use his circuit boards and modules, would like to add his plates and intermediates to my recipes)

If there are any other belt-oriented mods you'd like to see supported, please let me know. If you want to help me add support for another mod (especially if its your own mod), that would also be appreciated :)

Changelog:
16.4 - Fixed compatibility issue with bob's logistics, due to bob renaming his belts, causing his mod to overwrite Ultimate Belts top tier of belts/splitters/undergrounds.
16.3 - Fixed fast-replace issues when trying to replace vanilla splitters and underground belts with ultimate variants
16.2 - Fixed another recipe mistake
16.1 - Fixed Ultimate Splitter recipe mistake
16.0 - Update for Factorio 0.16, with help from zerotooll
15.2 - Removed production science pack requirement from logistics 3. Makes Ultimate Belts progression smoother. Also makes belts somewhat viable compared to bots for mid-game (using bob's mods ofc).
15.1 - Fixed typo in info.json
15.0 - Initial release