P5 UML (user on here) use to run with Eibach Pro Springs for his 325D E92 but has recently switched to BC coilovers (same as myself ~ E92 335D and N1 116 ~ E92 M3) and from hearing their comments and thoughts, both have spoken highly of improvement in the quality of ride over stock susp).
Matching springs with OE shocks IMO in the long run is a big no no and that pretty much swayed my decision in favour of the coilover suspension kit. Birds B3 in my opinion is far better because it is a full kit, not just springs. Springs will be no good if you decide you don’t like the drop / stance – as you’ll have to sell them on for far less than what you paid and eventually end up buying a full suspension kit / coilovers…
If those are your only two choices, my answer day in day out is the birds susp kit.
However, stretch your budget a little more and either buy yourself some BC coilovers at £690 Brand New possibly even a little cheaper or an even better set, the Bilstein PSS10 coilover kit which HotCoupe has for sale at the moment… that price is unbeatable and for that money, you will not, repeat will not find a better suspension kit.
I’m not sure whether the Birds kit is height/damp adjustable so someone needs to chime in please but this is probably the most important bit of advice I was given when shopping around…. Coilovers / suspension kit (not springs alone!) when adjusted correctly (i.e. damping / height) will deliver far better ride quality than OEM.. simple reason.. less body roll even on Daily Drives (and I never have been or plan to Track my car) and closer center of gravity. Get the damping wrong and you will ask yourself WTF is going on but get it right you’re onto a winner. The beauty of it is its fully adjustable ... How hard is it you ask? Well, open your bonnet, look top right and top left corner, place your fingers on the BC dials and turn right for harder setting or left for softer. It's that simple! Rears is the same which can be accessed from the boot.
Sorry to go on but I can’t stress enough how you may be dissatisfied with springs alone……Do it right first time otherwise you’ll end up paying more after a few months.
Now ask yourself what it is you’re looking for?
Any questions, feel free to ask.
BMW E92 335D | The Custom Cars
Last edited by AWBimmer; 01-08-2013 at 05:36 PM.