Hi,
the capacitors are Audaphon MKT foil condensators. The coils are Mundorf. So good quality components (especially compared to the stock cheap electrolytic cap crap), but not really high end. Components i've used in the end are about 16 euros plus shipping.
But i've tested some alternatives 4.7, 5.6, 6.8 uF caps and different coils 0.27, 0.22, 0.18 mH. So in the end material costs incl. tests were about 40 euros.
It's a roadster with wind noises and very nice engine noises and the speakers itself are OK, but really not high end. So i think extrem high quality caps and coils would be overkill.

My goal was a better sound quality without too much effort and cost.