Is this worthwhile?

[emily_mx5]

1) cut your springs, thats free.
or,
2) keep an eye out for good quality branded lowering springs in the forsale section. You can pick up a set of king or eibach lowering springs for as little as $200 second hand.

3) stay away from cheap ebay crap, it never ends well.

[lee]

Suspension forms the component which keeps your car off the ground. Don't cheap out on it!

I got Koni adjustable shocks from Shox.com ($650), Mazdaspeed springs from auctions.yahoo.jp ($250), and bump stops from fatcatmotorsports.com ($140). If I were buying again I'd probably go for Eibach progressive rate springs, but I like my shocks and bump stops.

[MattR]

It's cheap because you have to do a sh*t load of work yourself.

Going by the photo, all they are doing is replacing your springs and giving you an adjustable spring seat to weld on to your strut/shock body after you cut off the existing spring seat.

In the end you are better off going with either a new shock/spring package or getting proper coil overs.

The only time I would use something like this is for a vehicle that doesn't have an off the shelf coil over kit available, for example 240Z, that needs the struts modified and the shocks are a removable insert.