I checked into them quite a bit the specs vary slightly depending on the vendor. I contacted 2 EBay vendors selling them both were in Canada and then also looked them up in the Korean market. They are made in Korea and the average that they claim to drop the car is 1" to 1.25" depending on who you contact. They are not progressive springs so they very well may be stiffer overall ride.
The overall Info I got on all lowering springs lead me to decide to use either Megan (lowest cost avg $ 160 and good reviews drop 1.5" front and 1.12?" rear so they add a little more rake to the car but end up with almost exactly the same wheel well spacing many ebay sellers and Ive seen them as low as $ 130.00 but usually about $160-180 or Eibach from Kenectic (only avail from K5Optima store) at $ 325 and lower the car 0.8 in front and rear and are a progressive wound spring. Ebach has a great reputation and 100,000 mile warranty. IMO those would be the 2 best choices, I purchased a set of Megan and then decided Im going to go coilover so just resold them to a forum member the_owner he has a thread here and they look great.
The other common lowering springs are ARK - drop about 1.25" front and rear about $250 the have pictures on their site before and after. and D2 that are about 1.6 and 1.5" and their is a new company with a lot of vendors on ebay "Godspeed they are very inexpensive at about $ 125 and lower about 1.2 and 1.1" but have not seen many good reviews.
There are good before and after pictures for Megan, ARK, Eibach on thier sites.
Thank you for the very comprehensive response. I was hesitant on the Storm as well and they did not look like they were progressive. I wanted to go with coilovers but didn't want to remove them every winter. Choices are limited in Toronto as I didn't want to import them. I'll check if I can source Megan or Eibach locally.
I think best bet for the money is Megan but if you don’t want to go the 1.5” front then Eibach are your best bet but they cannot be purchased from Eibach as they are made for Kenetic performance by Eibach. So the only vendor I found in USA is K5 Optima store