i have a racing beat springs that i used for about a month and now it seating in my garage. ride was its the same as any springs like EIBACH and PROGRESS springs. ride height not too much satisfied with it unless ur planning to put a 16" or 17" wheels.
I hope the bounciness settles down or I'll have to go to coilovers just so I can adjust them when needed.
The best info I've been able to find is that the RB springs are 20% stiffer than stock and the H&R's are 30% stiffer, according to the following links
http://www.racingbeat.com/Mazda-2/Spring-Sets/77080.html
http://www.corksport.com/getting-down-with-the-mazda-2.html
RB's lower 7/8in front and 5/8in rear
H&R's lower 1.5in front and 1.3in rear
Eibach's are another option, they are 1.2in F&R, no idea how they compare in terms of stiffness
if u are interested in springs i'll be selling my RB springs soon. beware that this springs wont drop the car that much.
H&R makes 4 sets of springs with different lowering heights and spring rates which ones you referring to?
comparing both, the HNR springs give a lower drop at the front than eibach (around 1/2 inch diff). HNR springs are stiffer.
these are based from 1.5l a/t hatches here in the ph.
So while looking at all of this I noted some things which would help out our suspension in the front. Firstly when the car was lowered 1" there was only 0.5" of shock travel left before hitting the bump stops.
So I really hope that the instructions for the lowering springs tell you to cut the bump stops.
I also looked at the travel when the strut is in full droop. Overall the wheel has 5.5" of travel from full droop to hitting the bump stop. At stock height it has about 1.5" of compression so there is a lot of droop travel there. A shortened shock/cutting the bump stop will help there a lot.