What is the maximum sprint speed?

Solution 1:

What is the maximum sprint speed you can have?

According to tests made by some good guy on reddit, there is a cap of 10% sprint speed increase.

MIDA Multi-tool gives 8.5% bonus, adding mini-tool will adds 1.5%.

Are there more weapons with this effect?

Yes, any weapon with lightweight perk will increase sprint speed by 5%.

There are also items (e.g. warlock's Transversive Steps exotic boots) and skills (e.g. hunter's Keen Scout and Focusing Breathing) which are boosting sprint speed by same 5%.

Are they cumulative?

Yes, but due to cap it makes sense to use up to 2 items/skills with such bonus.