turbo backfiring at 3500 rpm under boost
 

Like the title says, my car is backfiring starting at around 3500 while in boost. I have an MK turbo kit. haven't had any issues with it other than this. Only seems to sputter and backfire under boost. I have a fab9 tuning coil on plug kit running denso IK22 plugs, MSPNP2, flowforce 640cc injectors, flex fuel sensor. I usually run around 50% ethanol (because Iowa) and 91 on the other 50%, if I can find 93 I will run 100% of that. I pulled the plugs today and they looked good, not fowled or anything like that. AFRs look good, low to mid 11s under boost. only running wastegate pressure right now until I get this fixed. Any help is appreciated, thanks!

Nailed it.

Whats the issue with them?

They're not real reliable, probably don't offer better spark than oem, are using a knockoff module, etc.

Pick one or more.

What would you recommend for a good upgrade?

Depends on your year car. For any car EXCEPT 99-00, OEM with gapped plugs and new coils/wires. For 99-00 (or any other year but especially 99-00), TSE’s cop kit is the most complete/easiest/cheapest on the market .

What he said. Or Sadfab-based GM truck coil setup. Or IGN-1A for a forever solution.

GM LS2 truck coil user here. And I'm using the right spark plugs.