http://en.wikipedia.org/wiki/Magnuso...s_Warranty_Act
The burden of proof is on THEM to prove that the downpipes directly caused HPFP failure. if they cannot prove this (and they can't, because the exhaust has nothing to do with the fuel pump) then they must replace your parts under warranty. Bring up the magic words "Magnuson Moss" and they should do it. If they still refuse, bring up the other magic word.. "lawyer". They won't refuse; it's a case they will certainly lose.