You might want to think about plugs even if you don't know how long they have been in the car. About 25K is max for a 335 with modified boost. You can get them for about $12 each. You will need a special thin socket, $20, to remove & install them.
2014 435M-Sport - 2013 135is Cab JB4/ISO 6MT - 2009 V-Star - 2009 Ford Expedition EL 4X4 - 2003 Xterra 4X4 - 1998 Ranger 4X4 - FFR Cobra MK-IV
work in progress