My Jeep has 90k miles on it and recently I’ve replaced all fluids and done a bunch of maintenance. At this point I figure I may as well change my plugs a little early and be done with my maintenance for a while. What are the best plugs to use? I’m willing to spend up a little for a little more performance as long as the longevity is still there (don plan to have to replace them ever again). Also, I’d like to do a compression test or leak down test while I’m in there. I’m going to do one or the other, should I get a leak down or compression tester and why? I’ve only ever done compression testing before on other vehicles because I never used to have an air compressor. Also any other work should I have done while I have the intake off? How often should the power pack (or what’re it’s called on top the spark plug) be replaced, and are they worth upgrading?