Vector 1,
The suspension geometry is designed for the 20-1 ratio. The 15-1 is way too quick!
I know the car feels like you have to turn the wheel a lot at parking lot speeds and will make you think you need a quicker ratio.
However, once you get rolling along this feeling goes away and the steering becomes quite quick due to the suspension geometry and dynamics of the chassis.
You will never be pleased with the quick ratio rack and it is actually dangerous as the steering inputs required with a 15=1 rack are way too small for you to be able control the car effectively at speed.
To make that rack work you would have to change the roll axis drastically which would require that you change the pickup points both front and rear and you would have to change the scrub radius and Ackerman as well.
Please change the rack back to the original 20-1 unit supplied by JBL as this is the ratio that I designed the chassis to use.
Nothing else will work!!!!
Glad you have that thing running finally.
Remember to get some heat into the tires before you use the throttle in anger!
PS: I would really like to see some photos of your dry sump system and the plumbing solutions that you came up with.