I put on my New Big Gun rev box the other day and started it up It sounded good, but when I gave it gas it would back fire and die out. If I held it at about 3000 rpms it would run but you could hear it backfire every few seconds. I could see the K&N Precharger puff out too. I have Dyno Ject kit, K&N and Core 4 pipe?

 

id say pu the old rev box back on and see if the problem goes away, if it does obviously theres something wrong with the new rev box...

 

It would be my guess as to it being the new rev box. Did it do this before changing the box?

 

No, I just wans sure if it was that or the combination of the box plus the jetting or what.