I have a 2007 chevy 1500 classic ls 4.8l v8, when I bought the truck dealership told me can only use iradium plugs, if you use any thing else it won't run right. Is this true or no? Have any yall used other types and had no problems? I do have cold air intake, throttle body spacer, 3in exhaust, and a bully dog programmer, 4in lift on ,33x12.50x17. get 18,mpg on hwy. looking for better plug to get better burn on fuel

 

With just that lil bit done you won't see a gain in changin plugs out for a better burn. Run the iridiums for sure though, doesn't like other plugs. Also get rid of the programmer and get in touch with blackbear performance or gowheatley and get a real custom tune. That'll help a lot more

 

I agree, go with the recommended AC plug... something I like to point out is the plug that goes in your truck 4.8L engine is the exact same plug GM puts in the Corvette 6.0L engine... its a good reliable spark plug and is going to give you the best performance

 

 

6.0 if you're goin to do the swap. Make it worth while, not much of a difference between the 4.8 and the 5.3 IMO. What gears do you have in it? That could help some. I also don't see how you pull 18 mpg with 33s cause I have the same setup down to everything but the programmer, I have a custom tune, but with 33x12.5x20 on stock 20s and get 15-16 mixed driving