Lowering 80mm will always give a hard ride, no two ways about it.
It's probably on coil-overs, which have come down in price in last few years but still start about £300 but some cheap kits don't tend to last too well with daily use on british roads (salt etc). Does give option to alter ride height.
Another option is lowered springs and shortened shocks (£200ish), then just lowered springs on standard shocks (£100ish)but the ride will be awful and going that low the springs might dislodge.
Fair play to going minus 80mm, I had mine that low years ago and kept losing the front spoiler, the corners rubbed on the road when cornering hard too!
