I'm a bit lost for words in here if I'm honest...
No matter what, get a spoiler, they're cheap as chips and easy to paint yourself off the car... I added one to my pov spec mk2 ph1 and it made a great difference.
Now, there was the nice bit...
Personally, I'd sell that bumper, it WILL look utter shite, putting two 6"
exhaust on there WILL look horrific.
Honestly, get yourself a dirt cheap ph1 172 rear bumper, (pick up one with the paint a bit tatty as you'll have to paint it anyway) but with no holes in it.
If you want a recessed exhaust, at least do it properly, and do a decent single slash cut pipe.
Next, I'd remove all the stickers from the rear window (maybe barr the CS one) and remove the rear wiper, it'll tidy it up 10 fold and cost nothing.
Then I'd stop wasting money on silly things and get those o.z f1's on.
Then, I'd lower it.
Then I'd make sure the paint was all good everywhere, and stop.