Anyone mount battery UNDER, or flush in trunk?

‘00 - 5.9, all stock except the following bolt on parts.

Edelbrock RPM intake, 750 carb, Lokar cables, OE trap door air cleaner, Hooker Super Comps & 1-3/4 - 2-1/2 true duals, long case Dynomax mufflers, older distributor w/MP Chrome box ignition, B&M flexplate for the neutral balance converter @ 2500 stall. FWIW, the rear is a 9-1/4 sure grip equipped w/3.55’s on 245/60/15’s on all 4 corners.
AutoZone aluminum radiator.

I know this is off topic but how does your car go with that setup?
You've offered some good feeback on my questions on my very similar setup but I don't know if I ever asked how you're making out with yours.