You have to tighten them down using set angles as they are stretch bolts, so they are disgned to be set under a amount of tension via the amount youve stretched them by (lol could have worded that bit better i'm sure...but its late)....using a torque wrench wont work. Just by a angle gauge...cheap ones are only a few quid and no matter how much it costs ie cheapo or Snap-on, they all do the same job to the same standard.

Stu.