Hey,
For all of you that used a down convertor to run your inputs into the amp, what place is the best place to ground the wire in the trunk. Also, is it really necessary to take out the old sub to get good sound? Does it really change it that much. And did you run a separate power wire to the battery or did you use the power wire for the OEM sub? Where is the factory sub amp? I'll be searching for some answers but any help or links to previous posts would help.

Thanks

94 LS400

was it you who aimed me about this? If not, ground it at the gas tank bolt. Make sure you send off all the paint from the grounding spot.

i grounded my amps in the wheel well, I just drilled a hole right through and bolted it straight to the chasis

The actual best place to connect this ground (assuming that you're referring to an LLC - Line Level Converter) is right at the ground of either the stock amp or the new additional amp. You can use one of the existing mounting bolts and connect to that, or just connect to the point where you've grounded the new amp. Try to keep the wire run short, or use the thickest wire gauge that's practical. The trick is to keep the resistance of this ground connection low relative to the amp's ground connections to minimize noise.
Yes, remove the old sub. Otherwise it will act as a filter that will not allow some frequencies to pass thru easily, yet allow other frequencies to pass thru where it is resonant. You can opt to leave it in if it's too much work, but your results will not be as good.