The price point that was posted earlier is for the RS-1 single adjustable for firmness/compression. I placed the email address for Erik. He will clear out all the pricing inquiries.

Why would you need to replace the rear air bags? That's an original BMW part, which you can get from any BMW dealer, the rest of the system is made by them. The rear of the E61 is self leveling, so i would like to keep that feature rather than change it out.

Why would you want it though? You are spending all this money to transform your suspension into something amazing with the JRZ and still retain the junk auto leveling. I am sure it still rides amazing but if you are going that far I would of just had them make a system omitting the airbags in replacement for shocks.

Ok, a lot going on here and some confusion has crept in.

When I referred to replacing the rear air spring, I meant simply replacing it OEM-for-OEM as this is a wearable part, much like one might replace control arms when replacing a suspension.

Island Road, to my knowledge most coilover kits in fact RETAIN the "horrible" air springs, but replace the accompanying shock. This is what the KW V3 does I am certain, and I had assumed this was the case with the JRZ. If the system doesn't at least come with a rear shock, then we aren't really comparing apples-to-apples with the KW V3. Are you certain that the other systems you mention forgo the air spring entirely? I'd be surprised, but I bet some folks here would want to know about such an option.

I would not want to lose the self leveling rear suspension of the E61.

@grilledcheese - Sorry if I might of caused some confusion in things, it was my understanding that the KW V3 kit actually removed the air suspension in the rear. After going though some of the threads here and then the KW site I see that it utilizes special links that allow the air suspension to lower itself with the front coilovers.

Apples to Apples are the KW and JRZ as they both utilize the rear bag as springs. I honestly thought they did away with the air spring. I don't see why anybody would want to keep that especially when investing so much money into a performance suspension, its possible it has not ill effect on performance and really only does do the leveling

As for FK I know that they tell you disabling self leveling so they are clearly not using it. As for ISC suspension they give you options to choose the front and rear spring rate. I am not entirely sure if they keep it or not. I will find out and update the thread as needed to keep all the information accurate.

5th option?
 

It looks like Fortune Auto makes a set for the E61 touring. They list it under their "500 series" model. I don't have any experience with them, so I can't speak to their reputation or quality. It seems they offer some customization options like swift springs. Not sure if their kit is front only.
If I remember correctly, they made a custom set for an E39 touring which replaced the rear SLS air springs too. I think they had to fabricate custom seats for the new rear springs. If you google E39 touring LS engine swap, it's the 1st result. They made the set for that guy's car and he goes very in depth.
Maybe they could do something like that for the E61? Just throwing it out there.

Thanks everybody. Given the approach of the "top" manufacturers to the E61 suspension, my intuition is that: a) the self-leveling functionality is perceived to be very important (RIHI's point, which I agree with); b) the air springs, when combined with an improved shock are not that bad from a performance standpoint; or c) both of the above.

This is precisely why I was considering installing new OEM air springs when doing this coilover project. Rather than viewing them as hindrances, it seems that these manufacturers are considering them an important part of the overall system.

It's the other way around. The KW's replace the rear shocks, and retain the airbags as springs.

Also, for anyone wanting to replace the air springs in the rear, Arnott also makes them along with a compressor, and they have a lifetime warranty.

https://www.arnottindustries.com/sea...el=86&year=203

Yes Exactly - That's unfortunate as its not a true coilover system.