To be honest, I don't think it would have fit. But even if it did, I would have done it this way anyway because it sitting over the fuel tank access, and should something go wrong, I wouldn't want electrical spark and fuel meet
Had a play with the amp today (quiet day at work)
Front comps are slightly overpowered by the coaxs in the back so turned up the gain on the fronts to balance out.
Overall gain has been upped and HPF on the amp as well as the HU is set to 63Hz.
These settings seem to work for the range of music I listen to.