So I picked up a set of BS Longs and have everything I need to install except an inch pound torque wrench.

How crucial is it to stick to the exact tightening specs per the manual? or can I just use my own judgement?

Forge.

 

If you have the touch, you should be fine. When i tighten down the exhaust to the head, I use a 1/2" universal 1/4" drive with an extension so's i don't over tighten.

 

Just use your best judgement and you should be fine. Make sure you go back and recheck the tightness after a few rides. The nuts will tend to loosen in time.