only brake upgrade i have noticed making a marked improvement is stainless steel braided brake line..
I have used Revival Cycles in Tx for (longer) line and the banjo bolts. It was a little tricky to get the line set in between the bolts b/c the inner polypropylene(whatever) is very hard. First time I did it, I thought it was tight and it popped while riding! Lot's of pressure there! Went back and did a much more thorough job in ensuring bolt was in the line as far as possible. This will take some strength to get done so get ready or get help! Been perfect since.