Hey I just installed my dual 12” sub and amp in my friends g35 but he had wiring done by some other guy. When I turn up the volume and set everything to max the subs are barely moving. It’s not the subs or the amp cause they were working on my g37. I didn’t see any connection from the rca to his stock subwoofer like i did with my g37. Would tapping into the subwoofers audio help? Or am I missing something. Cause I swapped the polarity already. I’m running a 1000w Boss class a amp with the mtx terminator dual 12”. Amp is 500w rms and subs are 400w rms and it was bumping in my g37. I don’t know what’s going on with his wiring.

 

Is the amp grounded correctly? Is the bass frequency set to the right decibels? Where is he getting the signal for the amp is it's not the rca's?

 

If the signal is not coming off the sub output its probably coming off a door speaker or something, and being crossed over.