BMW Performance springs - buy the kit, or go with different shocks?

[Black Gold]

Hey guys,

I am going to be adding the bmw performance sprigns to my 135i.

My question is, do i go for the entire kit, or go for the springs with different shocks?

My choices are narrowed down to 3

-full bmw performance kit ~ 1300 dollars
-bmw perf springs + koni fsd ~ 1200 dollars
-bmw perf springs +bilstein hd ~ 900 dollars

With the bilstein shocks I would definitely add the m3 front control arm kit because of the price difference.

I always liked bilstein products, but i want the most streetable LEAST BOUNCE PRONE ride possible

For people with expereince with any of these setups, what is your suggestion?

[cpt97m3]

I have the springs installed now, and next step for me is to add the Bilsteins. That's what I'd recommend since I think it's a better shock than the BMW ones. But the Koni FSD will ride very nice on the street.

[stevenc]

remember that the performance kit comes with sway bars as well..

[Dackelone]

Why not consider Koni yellows ?

[Fireflyer239]

My choice of the Bilstiens came from hearing good thinks about monotube dampers in general, and the company's reputation for consistent quality. I feel they are a perfect match for the BMWP springs, ideal damping for the spring rate. Together, they give a ride that is at one time incredibly comfortable while being very responsive and controlled, very secure at speed while encountering bumps, dips, expansion joints etc. Things that would once greatly upset the car are now handled very securely, at any speed.

To be clear, upon picking the car up from my installer and while just rambling out of the pothole-ridden parking lot, my first impression was of a softer feel than I imagined there would be. Upon shooting down some twisty backroads, I was extremely pleased to find lots of taut, firm control. I noticed much less roll, much more fun. After 1,000 miles, I'm still thrilled with how the suspension reacts quickly enough to take the edge off the sharpest impacts, while at the same time maintaining excellent chassis control during harder driving. Their ability to perform well through the entire envelope of driving conditions I experience, is what I wanted and what I got...and on the first try! I sense a high quality feel with these dampers, firm but never harsh, and very secure when pushed. I have to give a mention to the HP Autowerks control arm bushings for giving me more precise steering for not a lot of money. You won't be going wrong with any of your choices.

[Black Gold]

Originally Posted by cpt97m3

I have the springs installed now, and next step for me is to add the Bilsteins. That's what I'd recommend since I think it's a better shock than the BMW ones. But the Koni FSD will ride very nice on the street.

thanks. yea, my main goal is to eliminate bounciness on undulating pavement. i hate that twitchy feeling that has the car over-reacting to every change in pavement elevation....

Originally Posted by stevenc

remember that the performance kit comes with sway bars as well..

thats true. im not overly concerned about the sways, as i think id rather spend the money on the m3 front control arm setup.

but maybe the sways are more valuable than I think?

Originally Posted by Dackelone

Why not consider Koni yellows ?

i found them to be a little overly stiff in my previous m3. i like the monotube design of the bilstein over the koni yellow, but am intrigued by the technology behind the FSD's

i just want to make sure that the FSD or bilstein will provide adequate damping for the bmw performacne springs.

i hate the overly aggressive bounce you get from almost all lowering springs, and want to eliminate that as much as possible.

Originally Posted by Fireflyer239

My choice of the Bilstiens came from hearing good thinks about monotube dampers in general, and the company's reputation for consistent quality. I feel they are a perfect match for the BMWP springs, ideal damping for the spring rate. Together, they give a ride that is at one time incredibly comfortable while being very responsive and controlled, very secure at speed while encountering bumps, dips, expansion joints etc. Things that would once greatly upset the car are now handled very securely, at any speed.

To be clear, upon picking the car up from my installer and while just rambling out of the pothole-ridden parking lot, my first impression was of a softer feel than I imagined there would be. Upon shooting down some twisty backroads, I was extremely pleased to find lots of taut, firm control. I noticed much less roll, much more fun. After 1,000 miles, I'm still thrilled with how the suspension reacts quickly enough to take the edge off the sharpest impacts, while at the same time maintaining excellent chassis control during harder driving. Their ability to perform well through the entire envelope of driving conditions I experience, is what I wanted and what I got...and on the first try! I sense a high quality feel with these dampers, firm but never harsh, and very secure when pushed. I have to give a mention to the HP Autowerks control arm bushings for giving me more precise steering for not a lot of money. You won't be going wrong with any of your choices.

how does it feel over undulating pavement?

that is my main concern. my car with lowered eibach suspension feels like a bounce-mobile and I absolutely hate it.

as long as it isnt twitcy and over react harshly and bounce up and down quickly and harshly, im all in.

thanks for your feedback

[GaryS]

With Performance springs, the rear end will bounce about 1.5" going over bumps no matter what dampers you choose due to the soft stock rear subframe bushings. M3 rear subframe bushings will fix that. After that, there will still be a slight rear end bounce caused by the soft stock control arm bushings. I solved that with M3 rear control arms and Rogue rear toe arms. Sorry to bring bad news.

[Black Gold]

Originally Posted by GaryS

With Performance springs, the rear end will bounce about 1.5" going over bumps no matter what dampers you choose due to the soft stock rear subframe bushings. M3 rear subframe bushings will fix that. After that, there will still be a slight rear end bounce caused by the soft stock control arm bushings. I solved that with M3 rear control arms and Rogue rear toe links. Sorry to bring bad news.

thanks for the feedback

i guess the issue isnt that it bounces some, thats understandable on a street suspension.

the issue is the unsettled feeling and harsh movements up and down when the car is lowered. like a rapid slamming feeling, basically throwing you almost out of your seat.

in the end, ive decided to go with the bmw performance suspension setup in full and almost certainly adding the m3 front control arm retrofit kit

id rather not run the subframe bushings at this time due to the massive labor involved.

[crex]

Originally Posted by GaryS

With Performance springs, the rear end will bounce about 1.5" going over bumps no matter what dampers you choose due to the soft stock rear subframe bushings. M3 rear subframe bushings will fix that. After that, there will still be a slight rear end bounce caused by the soft stock control arm bushings. I solved that with M3 rear control arms and Rogue rear toe arms. Sorry to bring bad news.

+1 This has been my experience as well.

[HP Autosport]

Originally Posted by Dackelone

Why not consider Koni yellows ?

An excellent choice for dampers!