I’ve removed right around 150 pounds worth of interior from my car. As you can imagine, it’s pretty noisy in there. I drive between 1 t0 2 hours a day, half highway, half city streets.
If you are an audiophile, definitely don’t start stripping your interior. I haven’t actually used the radio in my car in a few weeks now, and I’ll actually be removing the radio entirely here soon. Wouldn’t really recommend long phone calls (which better be hands free!) either.
The noise level is definitely more pronounced on the highway (of course), but on city streets it’s really not noticeable.
If you are considering stripping the interior, but don’t want to deal with too much noise, my recommendation would be to leave the rear seat in. Out of all the things I removed, the back seat was definitely the biggest impact noise wise. The reasons for that I think are twofold, firstly, all the noise from the trunk (and the rear wheels/differential) all have a direct route to the cabin, secondly, the fuel pumps are located under the rear seat. Whenever the car is on, that whirring of the fuel pump is going.
Overall, I’d recommend stripping the interior to anyone who prizes performance over creature comforts. If you’ll die without being able to call mom while you’re driving, make sure you ask her for a power adder for your birthday.