New guide pins normally come with thread lock embedded into the threads. This will prevent the bolts from undoing after being tightened to the correct torque. Once they have been undone the thread lock is no good any longer. Decent replacement pads should have new bolts with thread lock as part of the kit. Buy OEM for peace of mind. Never skimp on brake components. You will need a short handled torque wrench as the normal long handled versions will not fit under a wheel arch.