Any non factory approved alterations to vehicle suspension geomoty should be illegal. Period.
Are you saying if I wanted to put after market springs on my car to drop it by 0.5 inches, that would be illegal but the VW sport springs that drop my car by 0.5 inches would be legal?
No, If VW says its okay to drop 0.5 inches then it's okay.
Why?? There are many, many cars that have been improved by aftermarket modifications, especially older ones. A 60's muscle car on a modern frame, with modern suspension and brakes is a hell of a lot safer than how it came out of the factory. I would say most of the people out there that modify their cars do it so they perform better, not lets cut springs and re-shape a-arms with a torch type of yahoos.
Dunno man. For a while, I saw quite a few people lift trucks using hockey pucks and longer leaf spring u-bolts.
Tell me about it....saw a 70s Ford pickup with a wood 4x4 installed under the leafs for a lift kit...... I agree, some sort of inspection would be a great idea. Now, whos going to form the oversight committee to make sure that the mechanics doing the inspection arent prescribing work to be done for extra income?? Also, how do you train said mechanics to know whats an acceptable mod and a hacked together, trailer park, "f$%k ya, she'll hold!!" garbage??
In NB for the safety sticker, if the car doesn't pass, the mechanic just slaps a failed sticker on your windshield. You then have two weeks to get it fixed. You can do the work yourself, get another shop to do it, or get the original mechanic to do it.
When it came to major modifications to the chassis or running gear, IIRC, you had to get a mechanical engineer to sign off on the work. Pretty hard to get that done, as most didn't want the liability. So they just never got certification and had to be trailered.
There was a guy that worked for us years ago that had a pile of money into a TJ. He couldn't get it passed. I can't remember the details, but it was a pretty egregious process. He eventually stripped most of the mods off, and sold it. He left the company about that time or I'd see if he could get me more details.