Hey all, im new to the evo scene but i have a problem on my evo 5 when im getting into boost at around 14.7 psi or 1 bar i start to get some jolting and backfiring, almost feels like boost cut? I was thinking the plugs could possibly need replacing? any info would help me alot thanks..

And also the evo is bone stock

 

Stock evo? NGK BPR7ES or BPR7EIX, if it's modded then go with the 8s.

 

I always use plugs that are 2 steps colder then factory

NGK Iridium "2-Step Colder" Spark Plugs (R7437-9) for evo 8/9 i dunno if they would work for the 5 i'd imagine so though

 

bone stock

 

Go with the 7s then. The copper (BPR7ES is much cheaper than the iridium (BPR7EIX), but the iridium last longer.