If you want to go with Lowering springs, i've seen people run Koni yellow struts/shocks with Eibach pro-line. Few have FRPP kit that comes with struts/shocks/springs. With just springs, your set on a fix height unless you start cutting springs. you can also go with Coilovers, this option gives you full adjustment on height and sometimes softness/stiffness. H&R, DGR, and Blisteen. Those are a few, there's alot out there for our focus.
I have the Steeda SRI on my 08. I love it but I will admit that I should have gotten the FSWerks CAI. I also have the FSWerks Race exhaust and the FSWerks 91 oct tune. I have yet to get suspension, but I know some people that are running Eibach Sportlines on stock struts and shocks and are doing just fine (For now at least).
steeda is a little more expensive then alot of competitors. however, they do make some top notch stuff. not sure if this is comparable, but the cobra we owned had steeda springs, they were awesome, lowered the car at a perfect height and pared with bilsteins they were road hugging goodness. they were a little stiff but thats what you get with the loss of ride height. you could also get the svt suspension, but that would require the omni kit from massive that gives you a wider variety of suspension options for your car. however, the cheapest out there right now is the FRPP kit and from what i've seen, people are quite content with it
FSWERKS CAI. Its a true CAI and will give you slightly better gains over the sri. and dont let people scare you talking about water potentially sucking into your engine. you would have to submerge your cai tube completely and be at wide open throttle for it to suck in water(=
The FRPP kit isn't necessarily "better" that's really up to you to judge.
Now I don't know the price but I think the FRPP kit bests any kit out there for price.
For a firmer ride and ~1.5" drop the FRPP kit is not bad at all I ordered from Tousley Ford in Minnesota and it was $301 shipped for 4 shocks, 4 springs, and all the other mounting stuff you need
I am happy with how it firms up the suspension but lowering cars is not for me, I am not happy that I lost 1.5" lol
I wanted to buy the steeda SRI but didn't have the $ so I happened to find a FSWerks CAI for sale in the for sale forum here and snatched a fairly new one up for $100 shipped  keep on the look out for stuff like that if you're on a budget