Next step recommendation

You're hitting tune limiters now most likely. Between that and the oem tune not being great to start with you most likely need plugs and a tune. But that may also mean you need new oem coils or fuel line or some other maintenance item first that was not mentioned yet. Tune must be safe and from a trusted tuner if you go that route.

I want to see the intercooler installed

I posted one on a car trying to test fit way back but the cost and mods needed to make it fit the customer was not interested in spending.

It's definitely not a bolt on affair. I had to trim the upper radiator support to clear the new temp sensor location and make new upper mounting brackets for the cooler and the condenser, trim the bumper cover/grill, and no crash bar will fit, unless it's on the outside of the bumper cover lol. But it does "fit".

Oh I'm aware as I had it on a car without the bumper attached.

What plugs do you recommend for your tunes?

NGK or HKS. Heat range and plug gap will depend on the tune and fuel used.