Rotorfreak

I have been getting this strange cracking noise from under the hood since i installed the greddy e-01 and greddy electronic boost guage...At first i thought it was the exhuast gasket on the manifold.. but it used to do it just once when i boosted for the first time.. sometimes twice but after that it would be fine... now i have installed a single turbo and changed all the gaskets still i get that cracking noise the first time i boost.. what can it be?? it also feels like it is coming from where i have mounted my greddy boost solonoid and boost guage.. but for now the boost solonoid is disconnected as i am running the turbo just on the wastgate for now but the E-01 is powered up cuz i am used to monitor the boost from it... the noise is still there..