what spark plugs are best?

I just replaced the plugs in my 2001 XJ. It has 71,000+ on the clock. I put in a set of bosch platinum +4, and took out the champions that were in there. I'm not so sure I like them. Has anyone else tried them? Do you like or dislike them? Do they really give you more power and better mpg's? I'm not so sure they gave me anymore power, and it's been way to soon to tell about the mpg's.

i tried them i only got 40k on them and they started to go bad. pulled them and put autolites in it havent had a problem with them yet

The champions work best because that's what the engine was designed for.

Yea i searched on bosch plugs in the I-6 and lots of people said not to use them, truck plugs deffinatly work good, went from bosch after learning the hard way to the champion truck plugs and i really did notice a difference in 1) engine idle smoothness (coulda been the gappign i did though) and 2. fuel economy went up.

I use Autolites or Champions in my 1990 4.0 I6. They last forever, much longer than anything I've run in a 4-banger German or Japanese engine.

I have used only the plus 4's in every vehicle I have owned since they came out. I currently use them in all 4 of my vehicles and have never had any of them go bad. Noticable power and mileage increases in all as well. Worth every penny of their price.

I've got a set of Champions that have been in the engine for at least 100k. Still running fine. Guess I've gotten my moneys worth!

I run the splitfires. Even though some people here will disagree, they've performed well for me. The next time I buy plugs, i'll probably try some of the plugs mentioned just to see what all the commotion is about.

I landed up buying NGK V-power plugs a while back and everytime i rev my motor (for intimidation cause i got a sraight pipe into a flowmaster 40),,, there is a lot of back fire at the higher RPM's.
So maybe i'll get a set of those champion plugs and see how they do.

Champion Truck Plug #4412

If you ever get curious, take a half dozen different manufactures plugs and measure the resistance between the cap and the center electrode. You´ll find some really large differences. And if you've ever have the opportunity to watch a plug fire on an oscilloscope and being able to freeze the picture, you´ll see why some work better than others.
The engineers give you an oscilloscope picture (usually produced with a specified voltage and resistance), that you try to match in the vehicle. Resembles a peak with a couple of bounces afterwords. I've seen the picture on the scope, look like static, which can´t be good. Some of it's plugs, some resistance in the wires and connections, some is how close the ignition module is to optimum. Some is even fuel, compression and valve timing.
There is a rather large difference between wrong, acceptable and optimum. Electronic ignitions, generally perform better anyway. But the engineers work really hard to get a predictable igniition and burn, plug splash messes up the works. More spark isn't necessarily better spark. Some octane knock, can be traced to plugs.
I´ve found in a system that's matched well, the plugs tend to last forever.

Been running OEM champion plugs for the last 275,000+ miles on my 98, tried NGK plats on my 87 Trooper with bad results, burned valves, tried fancy plugs on my 82 S10's 2.8L with poor results. In the end the trooper and S10 preferred coppers and the 98XJ is just happy with the OEM plugs. There was also a difference between the dealer supplied champions and the same plug model number I got at a parts store. The OEM dealer supplied one was heavier in it's component construction that was very visible to the eye when they were laying next to each other. I have not bought any from the dealer for a while and I heard rumours that the OEM plug changed so I may try the champion truck plugs if this is true.

I put Bosch plugs in my 95 a while back and lost several MPG,s. this is rhe second time Ive tried them In 2 different rigs with the same results. Trashed them and back to Champions. Must work in German cars only???

I used bosch double plats a few months ago and my engine ran worst than with the old champions. They worked great for my vw, but my jeep no-likey.

i needed plugs and just put in some autolites last night, boy what a difference in throttle response, those plugs musta been the originals from the re-build 30K miles ago the gap was way off.

I use straight Autolite coppers in my 98 XJ with 91,000 miles. Nothing fancy at all. Have worked great for the last 10,000 miles. I think its the copper that works better in this old designed engine better then the platinum.

that's what i thought to, copper over platinum in these.

thanks for all the opinions. I'm going to pull the Bosch out and take them back. I hope they will return them for me and give me my money back. I have been runing them for about 2 weeks, do you think they will refund? I'm going to by the champion plugs or the Truck plugs. Thanks again for the help!!

Snowball's chance in hell.

i once ran bosh 4+ in an iron duke i could see a diffrance in power till one of the plugs blew up and took a valve out. i drove the car for another 6 months till it died.