Just so you can understand also , my 2000 and 2001 with the same type of tag,like the one under your hood does say champion plugs, as does the FSM , just so it's understood.(Also it doesn't say anywhere ngk)

 

Not trying to step on any toes, but EVERY Jeep dealer where I live say that NGK IS the plug to use in the 2000-2001 distributerless Cherokee with a 4.0 6 cyl. engine. I do not have a distributerless Cherokee so I do not have a sticker to verify this by physically checking it with my own eyes. I can only report what the 4 dealers in my area tell me. Just sayin'

 

I use Champion copper plugs in the 87-99. I use NGK copper plugs in the 00-01.

Champion coppers will work fine on the 00-01, BUT the NGK gap seems to hold up better over time than the Champion (less gap widening). The ignition system on the 00-01 is a little tougher on plugs than the ignition on earlier XJs with the distributor.

But as long as you don't go much over 30k, you certainly can run either.

 

Here's a good chip: http://www.ebay.com/itm/PERFORMANCE-...#ht_4217wt_924

It says it gives you an extra 75 hp and an extra 25mpg

 

If you want actual performance increase, shell out the money for a tuneable ecu (apparently these are not rewriteable) and have it dyno tuned. I've done it to every one of my GM vehicles and it was definately worth the price ($1200 between 3 vehicles). If you want a turbo or some wild mods, go for a piggyback system that supplements your factory system. Anything can be done but it all costs $$$$$$$$$

 

HAHAHAHA!!! Maybe 15hp and 2 mpg out of the world's best tune lol

 

Why are people complaining about plugs other than copper? I have been using bosch platinum for 2 years and i dont think i have once heard a misfire.