So this is about an EJ9? I have had a standard DC2 and I absolutely never felt I needed different suspension. It was also really good at handling worse roads. Besides that, your suspension is a lot more than only dampers and springs. It's also bushes, anti roll bars and more. So one alternative you could consider for the same money as a brand new coil over set:
- Stock low mileage second hand EK9 suspension
- EK9 arb's
- Lower rear brace (needed to handle the EK9 ARB's)
- New bushings, perhaps of the stiffer kind
- Suspension components that make adjusting your setup possible, for example by Skunk2
- If there's budget left, bracing for your car
Another advantage is that the lowering won't be that extreme, as you're looking for not too low.