I've been distributing BC for California over the past 10 years to fill a void for affordable suspension that's well supported for our dealer network. While they won't have the same valving technology of say KW or Ohlins they definitely can be an improvement over the stock suspension setup because we can customize the shocks unloaded/free length as well as bump. I've already taken apart the oem spec'd BC's so that I can have them custom spec'd to suit our calculations for wheel rate, stroke, etc.... BC is a massive company and many of the other "affordable" coilovers you find on the market from Taiwan are private labeled BC's and will still come through their pipeline but is from a lower end series, V1, hence the reduced pricing. Many of the others are the 50mm shock bodies whereas the BR series is a 52mm shock body. BC does make the DR series as well which will give you the digressive valving that so many talk about. I am looking for someone to test out my custom spec BC's but ideally need someone local to Fremont, CA. If interested lmk. It takes about 4-6 weeks to get them spec'd and to the states.
In regards to installation, there is something technical you need to know when installing a suspension similar in configuration to BC Racing or many other types of similar coilovers that have an independent lower bracket. KW/Bilstein are great in that they make the installation very user friendly because they remove all the guesswork for you by producing a fixed "damper length". I won't go into too much detail but there's a fine balance between droop/rebound and bump/compression travel in relation to the overall "critical shock length". Most consumers are unwilling to pay the costs of setting up a "JDM style" coilover properly and resort to adjusting all the ride height at the lower bracket which is technically incorrect. There's a very good reason why the european brands, Ohlins aside because it's a Yamaha damper, do not believe in these independent lower brackets. It's all about threaded fixed damper lengths and longer strokes. I don't question the europeans when it comes to dampers and other things alike.
If I were to install a BC racing, RSR, etc... type of coilover onto a car it would be a multistep process if I haven't done one before. I would remove the spring, disconnect all the sway bar end links, then install the damper, adjust the length such that under full compression there is no contact with anything including control arms, sway bars, tire to fender liner, etc.... Once that damper length is setup then the spring can go back in and adjustment can be done at the spring just like KW/Bilstein/Eibach/H&R. Many times we will add in a helper spring to maintain spring position if needed. The Model 3 is a bit unique due to the amount of preload and spring rate we run on them for street cars so we have not needed a helper/tender spring as yet up front. Now with Tesla we have another metric to consider which is battery pack contact so add that variable into your damper length adjustments. Ideally we want the bumpstop to be fully engaged before any of these areas can make contact with anything we do not want it to. That's a real short dirty version of some of the basics to consider.
