The roads are terrifying lol.

If they aren't lubricated properly that will happen unfortunately. Overall I think the rtabs are the ones with the highest NVH increase. I have no experience with monoballs but I hear they are very good.

Yah poly ads NVH noise vibration harshness but it feels so good !! My e46 feels like a race car with all poly bushings 💯 I like the soft oem bushing but the performance that poly gives you is so worth it 💯🤷‍♂️car feels so solid around corners

The creaks and rattles are from the stiffer shock/spring setup paired with the cheap plastic interiors these cars are known for. Poly may add to this in some locations, but for the most part, it will come down to how well the shocks and springs can absorb the bumps in the road. I also had a lot of things in the car at the time so most of the noise is my stuff rattling in the door panels and glove box. I hope that answers your question 🙂

Those are the 3 places that will create the most NVH. I have 75d diff in my car, they introduced a small whine as they are very stiff but not bad at all. Engine/trans will vibrate a lot at low engine speeds. Really it's car by car for those. And how often you drive it. If you do engine or trans make sure to do both so they are the same stiffness. You don't want to mix and match otherwise you risk money shifting. Personally on a weekend car I'd run all 3. For a car I put a lot of miles on I would do diff again but avoid engine/trans. Feel free to ask any other questions! Edit: I am not sure what car you have but you might want to try suspension too if you are getting twisting under acceleration. On the e36 I installed poly for the rear trailing arms which helped stiffen up the rear end a good deal when cornering or applying engine load.

Depends on the bushing. The inside is supposed to be lubricated on most of the AKG bushings. AKG says not to lubricate the outside. I did on most of them and haven't had any issues. It helps with squeaking.

Yes and no. If you have a bad or worn differential, you will hear a whine. I do not have a whine on my car most of the time. One time, I removed the rear seat to diagnose the fuel pump, and I heard a very slight whine since it was acting as a sound barrier. But quiet otherwise. However, I have 75D poly in my subframe and diff. While it is technically solid from a movement standpoint, it still has some of the NVH dampening of poly that aluminum or various metal solids lack. Solid subframe will not usually cause diff whine, depending on the design of the car. Solid diff will run that chance higher. If you are bothered by it but still want solid, I would get a solid subframe bushing and a stiff poly diff bushing. Or frankly, don't get solid if NVH is a great concern. Poly will be close to the performance of solid without a lot of the drawback. What car do you have? And what is the intended use?

@@M-t3ch I have a Nissan 350z that will not be tracked or at the strip. I recently put in engine and Transmission polyurethane mounts and they are a little whiney but they need to settle in then they'll be good. But if the whine from the diff and sub metal bushings would be like the video then he'll no. That is why I was asking would it be like that?

@DragoMusivini I am unfamiliar with that platform specifically. But if I were in your shoes, I would not do solid diff bushings. Subframe, you'd probably not see any whine. However, you aren't going to see much performance benefit on the street over poly by running solid. Solid bushings are not a great idea in general if NVH is of concern. They transfer everything to you, whereas poly has some vibration dampening properties. TLDR: Go poly or rubber for the diff.

@@M-t3ch I never use rubbers......lolololol.....anyways poly is the way to go then thanks.

Why do you say that?