Objective bushing comparisons

[Maybe Magpie]

Has anyone done one before? A lot of companies (AKG, Condor, Garagistic, et al.) insist their bushings don't increase NVH but I hear the exact opposite almost universally from other E30 owners. Durometer is durometer but I'm curious if a high durometer rubber and high durometer poly have the same characteristics in terms of NVH, and which bushings to avoid using poly for if I want to keep NVH to a minimum while improving over stock. "Oh they don't squeak and rattle" "Yes they do" he-said-she-said is hard to discern. I would have gotten the Group N bushings but they went out of production sometime after 2019 and are NLA, they're essentially stock but solid rubber.

The thing is one person's "fine" NVH is another's "miserable", so I was hoping to find some sort of meaningful comparison, if not of bushings in-situ, of materials and durometer ratings and the like. I mostly street my car but I don't want to rattle my teeth out on my area's shitty roads. I know the E30 is a 40 year old car, I don't expect it to be silent or perfectly smooth but it's already vibrating enough as it is with an exhaust on it and I don't want to make it miserable to daily.

[digger]

This is a loaded question as the specifics and details matter including the operating environment (type of road surfaces and imperfections encountered) and the application e.g. which bush in particular and intended usage and then there is personal taste/perception and point of reference.

The softer poly might be acceptable to some tastes on certain bush locations depending on usage but will never be as comfortable as the OE rubber period. E.g. Antiroll bar bushes are pretty safe though companies like whiteline and H&R use a better poly than places like IE whos bushes are rubbish (unnecessarily hard)

Which group N bushes are NLA? sub frame were last time i looked

[Maybe Magpie]

This is a loaded question as the specifics and details matter including the operating environment (type of road surfaces and imperfections encountered) and the application e.g. which bush in particular and intended usage and then there is personal taste/perception and point of reference.

The softer poly might be acceptable to some tastes on certain bush locations depending on usage but will never be as comfortable as the OE rubber period. E.g. Antiroll bar bushes are pretty safe though companies like whiteline and H&R use a better poly than places like IE whos bushes are rubbish (unnecessarily hard)

Which group N bushes are NLA? sub frame were last time i looked

Those are the ones I meant, yeah. I haven't ever found Gr.N bushings for the RTABs et. al or anything else, despite some hunting. Wide open to P/Ns if you got 'em. FWIW I'm in the PNW and here we have a ton of elevation and while a decent amount of our roads are okay in smoothness it's really not uncommon to find enormous, shockingly deep potholes or cracked up surface. Some of the more important stretches of interstate are in a not-great way, too.

The thing about it being loaded is that's why I want to figure out some kind of baseline and work from there. For my purposes of street car with occasional autoX and spirited backroad that I daily I want something quite soft but a little stouter than stock, the problem is I don't have access to an E30 with poly to compare NVH against mine, etc. I know durometer is for hardness, is there a good measurement for vibration transmission? Something to do with frequency, maybe?

[digger]

33311417247 group N rear subframe bushes can still be found. they arent cheap and tbh i have a set (not installed) and they are at most a subtle upgrade as the rubber is supposedly slightly stiffer but the geometry looks the same not completely solid. Better to by a stock set and fill the voids with 70 shore A casting rubber. It is possible the legit Group N are superseded and now just the stock version is sold under group N guise (based on what i received it wouldn't surprise me)

https://www.m3-klassik.de/images/TK_E30_N.pdf