I don't think "The Explosive Child" is for normally misbehaving kids, FYI.

And I don't think it matters whether your son is overexcitable or just naughty. I think the consequence is the same.

When my boys were that age, we did timeouts, but we also had a marble jar for good behavior. The kids really appreciated being recognized for doing something kind, helpful, cooperative, or any other thing we wanted to encourage. When their jar was filled, they got to choose an outing or treat. Honestly, we didn't fill it that often, but it was the act of being "caught" doing something good that mattered to them. I wonder if you can talk to your boys about behavior expectations, especially about being kind to each other, and set up rewards for good behavior, or simply just start commenting on good behavior, like, "Wow, [older brother], that was so thoughtful of you to let him go first this time. I really liked seeing that." It sounds like your older son is feeling competitive with his younger brother, so my focus would be on getting them to do kind things for each other. I think positive reinforcement is more effective that consequences.

As for the clothes throwing. Consequence for sure. That would require him to pick it up and also give a time out in his room for disrespecting you for throwing the laundry.

Another effective consequence for my kids was a Mitzvah. We're not jewish, so I'm not sure we did it right, but in our house, the transgressor had to do something to make up for whatever he had done wrong. In the case of the clothes throwing, this would be folding your clothes in addition to what he threw around, and maybe doing the laundry. If it was something involving his brother, you might ask the younger what would make him feel better, or how his brother could make it up to him. We had some creative punishments as a result of this, but the transgressor had time to think about what he'd done, and the "victim" ended up feeling valued and appreciated.

Also regarding controlling emotions, it's very common at ages 4 and 6 for them to be overexcitable. When my kids would try tantrums at that age, we would totally let them, but would ask them to go to their rooms to cry because it hurt our ears. We never told them how long to stay, just that they should stay there and relax until they felt more in control. It wasn't a punishment, so much as a way for them to settle down and learn self-control.

And finally, my soapbox. Please don't buy into the idea that gifted kids can't control themselves because of overexcitabilities, or that they need some other kind of rules. Gifted kids need to behave just like every other kid out there. I know you're not saying they don't, but many parents think that of their gifted children. The way one handles a gifted kids' bad behavior might be a little different, but the expectation should be every bit the same. We're actually removing one of my children from our district's highly gifted program because there are so many kids in the classroom who don't behave. Their parents think their kids are precious snowflakes who shouldn't be expected to be quiet, sit in their seats or be respectful, and they literally say that to the teachers. I'm frustrated that we have to move my child, rather than the naughty children moving, but it's a losing battle. Thanks for doing your part early, to make your children good citizens.