I went through with an aftermarket pod filter. He asked if I had any mods - I said the only thing I am aware of is the Pod filter he said and I quote "nah, you don't need an engineers cert for that". Also - coilovers were accepted, however it needs to be legal height and correct parts. ALSO I had a turbo timer which they asked about, "is that a turbo timer?" Me: "yes but i can force it off by lifting the hand break" him: "demostrait please - okay all good".So there are a few things you can pass that is not factory but if it's easy to change out id recommend it.
I passed 2 weeks ago - I'm sure it's a case by case - also I acted as if I didn't know anything about cars (which is pretty close to the truth haha) and so they were quite helpful and lenient.
Edit: I also got a Trojan to fit and install parts so it looked as if I wasn't doing the dodge and that the stuff was correctly installed - which helped A LOT ! As they questioned things and after I gave my invoice they didn't check the installed parts and just ticked the boxes the invoice said was complete.