hi and welcome
, good advice already but heres mine too
First off JKM are
, good hands so no worries there.
Get a before dyno plot before you touch anything too as a baseline.
Consider if this is going to be the end of your modding (realistically) , which I would suggest it isnt. So dont waste money on 'partial/ineffectual' mods
So hold off on the filter until you can afford a full replacement item (Twintake or ITG) +20bhp , panel gives little or no gains, stick with the OE aribox until then
Same with exhaust , either get the full Turbo Back Exhaust (TBE) or leave original , same principal gains are in full system not cat back (plus you have duplicated labour costs if you do it in stages)
S3 Ic i would suggest isnt required at stage 1 for your usage.
Consider the Forge Twintercooler as its good too and easily removeable, if you arent fitting it the labour is high for fitting an S3 cooler for limited gains
Brakes you 'can' live with but in reality they are marginal at best on a mapped ED30 dependent on your driving style.
Also consider good quality tyres depending on whats on just now
Id also be looking at uprated engine mounts , either just gearbox or all and a WALK kit. (see product review section)
(I assume you are a manual car? , in which case yes budget for a clutch if remapping....)
hth
John