I will be TOTALLY honest with you on the sound.
The bass doesn't push quite as hard as I would like it to.
If I was too keep it, I would either fibreglass the inside of where the sub sits and have a larger enclosure, made from the actual structure of the depths of the car, for solid sound. Letting me use a ported enclosure, for better sound.
OR ... just put a ported enclosure in the boot, where a nice 10" will easily sit and still not be seen from the outside of the car.
Stealth was always the aim with the system.
Saying that, the Rainbows are incredible... and produce enough bass themselves for a lovely sound.
I keep meaning to take the door skins off and dial the tweeters back slightly, as they are a little sharp for my taste and you can alter it with jumpers in the cross-overs. But I have done that with the EQ on the HU.
I have fallen in love with the Genesis amp.... ended up putting THREE in my campervan, matching them with Rainbows again.
Although I am sure you could come down and make some amp/EQ recommendation's to make it sound better