Spike lugs?

Hey everyone,

I have recently picked up a yellow FJ Cruiser, and I am totally happy I got it, as it was my dream for several years.
There are certain things I plan on improving about it. Yet, there is one question I am eager to ask you folks. Is here someone who is familiar with spike lug nuts?
I plan on putting yellow spike lugs on my FJ, yet I have never had them in any of my cars, and do not know much about them.
Here are my main concerns:
1) Are they street legal?
2) Do they make extra noise?
3) Is it better to pick one- or 2-piece lugs?
4) What material is better: steel or aluminum?

Many thanks.

Just keeping you posted, folks. I picked up a set of steel lug nuts by Hunting Horse from Amazon last night (just like [URL="https://spike-lugnuts.com/colors/red/hunting-horse.html"]these spike lug nuts[/URL], but in yellow).
I've read that steel ones are more durable than aluminum. Plus, the paint lasts longer on them.
Anyways, I will give them a try and install them this weekend. If you are interested in how they look on the FJ, just let me know, and I will share pictures here.