Just wondering if i can improve mileage and performance in my 3.9L with better plugs??
I have put a K&N air filter in it and that is it.

 

champions suck.... pull them out easy and get some bosch plats for splitfires... i had a set of champions in a chevy 350 that one sheared off between the threads and hex.. champion swore it was my fault.. i had to pull the head and extract the plug.. my opinion..

 

ok i understand you had some problems.....but is it worth me replacing them ....as in better performance,
i see claims of sparkplugs improving mileage and permance is it true?

 

There will be a minimal difference, but you wont be able to really notice it. if you havent changed them for awhile it could never hurt......as for bosch idk about the v6's but bosch for the magnum v8's dont mix very well from some of the posts that are on here, nomatter what breed they are....champions or autolights are actually what people reccomend for these trucks with the magnum engines, just do a search on some of the threads if you dont believe me:

 

What is the average life span / mileage of a set of spark plugs?
How often should they be changed?

 

Well...........its depends on how you drive it and the conditions you drive in, also if its more city driveing, more highway driveing, or a fairly equal combo......any idea the last time they were changed?? IF they are factory then it should be every 30k-60k......i change mine every 40k, but it depends on alot of factors.

 

I got 19,000miles on it and they have never been changed.....its a 2004, and i have half and half highway/city.

 

You should be good till about 35-50k.......again you wont notice a difference nomatter what plug you get.....if it was me and your truck, i would just let them be for the time being.

 

awsome! thanks for answering my questions!
anything else i can do for cheap to fix up my truck?

 

To fix it up.....ummm whatever the manual reccomends for general maintance, although your truck should be good with that low of miles for quite some time. You fluids and what have you should all be very good condition still, but once they reccomend you change some of them, performance wise and durability wise, maybe look at an entire synthetic fluid kit from Royal Purple. They GARUNTEE up to at least 10 HP, and that stuff really makes things slippery and smooth, although im not sure on the price....but it'd probably be worth it. Also, its not cheap but with your K&N, put an exhaust system on your truck that will give you some ponies-for performance, along with a programmer or chip, but those are definatly not cheap, they will give you a better mileage and more power too. You could really go overboard with headers and all of that, just depends how extreme you wanna get haha. Easiest/cheapest way would probably be Royal Purple, when the time comes to change out the factory fluids that is.