We've got two performance model 3s one outfitted with the
@MountainPass Comfort Adjustable and the other with the Sport Adjustable coilover. Both sets of Springs are very comfortable but the comfort kit (set at its defaults) of course is quite amazing. If you can afford it, a full coilover kit it is always better than simply doing springs and the worst part of the stock suspension is not the ride height it's the crappy shocks and on the older cars the very premature recruitment of the bump stops which yields some significant handling anomalies.
Lots of people who put just aftermarket springs on have been dissatisfied including having a lot of trouble finding and quieting noise from the aftermarket Springs whereas we have no suspension noise at all on our cars of any kind. Handling with the Sport kit is just outstanding particularly if you combine it with MPP's great front lower control arm bushing kit. Highly recommend that combination if you're looking for great handling or the bushing and the Comfort adjustable kit if you're looking for the best possible ride also with significant improvements to handling and roll control. Mountain Pass kits are highly adjustable so that you can set them up either for track or touring and their support is the best. This is like my 15th coilover kit and these two kits are the best by far.