It has been approximately 7 hours since my new H&R Sport/Bilstein B8 suspension set-up was installed at EAS, so I decided to post a mini-review regarding my initial impressions of the upgrade. Due to the fact that it has been raining here in Southern California, I have yet to fully put the car through the paces, so I will likely add to this review over the next few days as the weather clears up.
On to the review....
Most of you were already aware that I was running the H&R Sport springs with the OEM M-Sport shocks for the last month or so. While that particular combination works, it wasn't an ideal set-up for me based the type of suspension feel/feedback that I prefer (..
stiffly sprung, stiffly dampened, etc.). This led to conversations with
Rich over at GTB about upgrading to the Bilstein B8 suspension. With a bit of coordinating between the two of us, a Group Buy was presented to the forum and I promptly placed my order. The suspension arrived promptly, and I wasted no time making an appointment to have the suspension installed. As I made my way to EAS in Anaheim, California, I paid particular attention to every nuanced response that the H&R/M-Sport combo provided. I drove with the radio off the entire trip, and had decided to take the same back roads to and from so that I could objectively assess the differences.
After the install was completed, one thing stood out to me almost immediately:
the car sat a tad higher - maybe 3 to 5mm - in the front with the Bilsteins compared to the M-Sport struts. This may be due to where the perch is on the Bilstein strut relative to the M-Sport strut, or it could be due to the stiffer dampening (..
I didn't think to do a side-by-side comparison prior to the struts being installed). The minor height increase didn't bother me, but it was worth noting for the purposes of this review. The stance of the car is still visually appealing.
edit:
I did perform a quick Google search about the minor increase in ride height, and it seems that people who have installed Koni's and Bilsteins have noted this (...
I knew I wasn't crazy!!! 
). It was also noted that the struts/shocks did settle a bit and the ride height was reduced.
After the install was complete, I was eager to hit the road and assess my car's improved handling abilities. What I noticed
immediately was the feedback. I can now feel EXACTLY what the road beneath me is doing, and the suspension is communicating the road surface/texture differences very clearly. With those attributes comes a bit more road noise, but I don't mind that at all. In fact I prefer it. Lateral body roll and forward/rearward pitch [during shifting] is nearly non-existent (..
and I can finally put those adjustable side bolsters to use; up until today I really didn't need them). This is the feel/feedback that I've been longing for.
Turn-in feels accurate and confidence inspiring, and I can more accurately gauge the performance of my tires. I used a cloverleaf freeway entrance to test the lateral feedback of the suspension and the tires, and I now feel like my tires are the limiting factor (..
and it is also easier to interpret/understand what the tires are doing with the Bilsteins). The suspension was up to the task while I felt the tires were on the cusp of breaking loose into a [controlled] power oversteer. I will test this again on my local "
proving grounds" in the next few days.
Another minor issue that was completely eradicated by the Bilsteins were the rare occurrences of rubbing caused by my aggressive rear wheel offsets. Although the rubbing only occurred on the most egregious of bumps (..
due to the M-Sport shocks bottoming out), it would still make me cringe a bit each time it happened. I had previously attributed the rubbing to the mismatched suspension components, and I was right. When I tested the suspension this evening on those unruly road undulations, the car didn't skip a beat. I made two passes.....increasing my speed as much as 20mph faster than my usual travel speeds, and the car just stormed through like a champ as though the undulations didn't even exist. Well done 335i....well done!
Overall, I believe this kit is the best "
bang-for-the-buck" for those that don't need height adjustability, and who are looking for a drop beyond that which the OEM M-Sport suspension provides. The M-Sport suspension is already very good from the factory, it just leaves more to be desired if you plan to add a spring that provides an aggressive drop like the H&R's do. If you decide to opt for the Bilstein/H&R combo, do yourself a favor and have the H&R's installed at the same time that you have the B8's installed to save on labor costs. I could've saved $250 by doing this the first time around, but to my defense, the stellar Group Buy wasn't presented until a month after I had installed the H&R's (..
and I really hadn't put too much thought into the B8's prior to that). All this combination needs now is a set of sway bars to pair with it.
Rich.....let's get it going!
Lastly, this set-up will make you want to drive (..
much the same as a good coilover set-up). The car is significantly much better behaved around corners and through transitional movements, and it will beg you to test its newfound limits.