problem with my viper 5901?

A better question (I think) is where/how is the shock sensor mounted?

If it is a external shock sensor...Try to mount it to a big loom of wires under dash...If it is internal shock sensor try moving the brain to a better location(wire loom also). On some vehicles that have the firewall padding,ive been able to slide shocks betwwen padding and firewall...Also to make sure the shock is working drop shock/brain...arm alarm...Flick the shock/brain and see if it triggers alarm...Good luck

it is a internally shock sensor. i moved the brains and the zipped tied it to a wire loom and part of the dash. it works good but it not super sensitive as i thought it would be. Is there some add on sensor i should get to help?

You can add a second shock sensor...Put it in RF or RR...In most cases, you do not want the shock sensor too sensitive...Every loud Exhaust...Big Truck...and Loud car will set it off...Set it well enough that you can get warn away chirps by hitting vehicle w/ the ridge of your hand... 360 around car...If coverage isnt great,,,Again try to relocate brain...Add 2nd shock...Maybe even a proximity sensor...