Spark plugs?
 

Denso plugs were in my lightning when i bought it. Are they a good plug? Is there a better plug to run?

the denso iridium tipped plugs are the best money can buy. I would stick with them or the motorcraft double platinum plug from ford.

I agree with Heavy, I use the Denso's and love em.

you may want to check out the brisk plugs
they are getting 10 hp out of them on the cobras

For me there was a 10hp difference over NGK TR6 plugs while on the dyno, and that was with a broken electrode on a Denso.

I just put the Brisk in mine and they seem to be just fine. Never tried the Denso though. Think the Brisk are a little more expensive. Paid 100 bucks for the set.

seems alittle expensive for a set of plugs, but $10 a horse is not that bad.

I paid $15 a piece for the denso's in my otherwise stock 4.2L, noticed a big difference in upper RPM's.
Scott

I've run both the Denso IT-20s and the Brisk plugs, which are in the truck now. I picked up 14 RWHP on a Mustang dyno with the Brisks and charted the pulls for Mark Silvestri at LFP. Both plugs work really well and provide excellent longevity. The biggest difference is that the iridium tipped Densos don't like nitrous, whereas the Brisk plugs handle it just fine.

yeah the iridium tipped denso plugs burn hotter , that is the reason for the pickup in performance with nitro with the colder burning plug.

Have not yet changed plugs (39000km)
 

I have the orignal plugs. Will Dense or other plugs make that much of a change?

I also have o.e plugs with 18k miles but I have also been having engine troubles that my dealer cant seem to fix. They replaced a couple coil packs but still runs at about 2000 rpm with a skip like feeling! Not sure if it is spark or fuel. Seems like something they would be able to fix. It also set the check engine light once. Any hel pwould be app.