Sometimes peer pressure can have a positive effect if it means that you do something that you've always wanted to have a go at, but have lacked the confidence to try it.
Things like going on a scary ride at a theme park, or trying windsurfing are always more fun with a friend. Trying new things helps you to develop confidence in yourself.
It is okay to disagree with your friends sometimes. You don't have to agree on everything all the time. A real friend will respect your opinion even when it is not the same as theirs, and will not threaten to end the friendship unless you think the same as they do about things.