Do ppl think I require an even colder plug than my current Denso ITV-22's?

When planting the throttle in any gear, the boost will kick in as normal, but then a massive backfire, popping and instant powerloss occurs. So much that it makes you rock back and forth in your seat, which just continues unless I pull my foot off the pedal.

But when I floor it gradually, you get a big hiccup but unlike flooring it hard, it powers through to top end with ease...

So do ppl reckon I require the Denso ITV-24??? Or is it too cold a plug for my mods...

Mods are as follow...

Milltek Decat,
Milltek System and flexi pipe,
Gen2 K&N,
Bluefin,
Piper 270 Cams,
Ford Motorsport Manifold,
DV26 Dump Valve,
Denso ITV 22 Plugs,
Magnecor Blue Leads

291.2 BHP @ 6580 RPM
339.8 lbf-ft torque @ 4500