Amp grounding spot

Alright guys, I've got a question here. I have a kenwood 1000w peak monoblock amp mounted underneath my driver's seat in my 2006 double cab. The power and ground wires are currently 10ga. and I'm in the process of changing that over to 4ga, however, I have my current ground ran to the rear passenger mounting bolt for the seat and was wondering if that is a good enough ground to wire 1000w amp connected to two kicker cvr's wired at 2 ohms, or if I need to ground it elsewhere?
Thanks in Advance.

 

The spot your using is probably fine, but I'll poke around under the driver seat today and see is something looks shorter. My immediate thought is to use one of the 12mm or 14mm( I cant remember which size off hand) bolts that the seat mounts to the body with.

 

That's what I'm currently using.

 

Grounding points generally work but a solid ground to the frame or major solid structure works better. Ensure that you Sand down to connect zone to get a solid connection. If your grounding to what most would do, the body, ensure that you also upgrade the grounding points up front that ground to the body.