I have a 2015 GTX 260 and hacving performance issues (7000 rpm max and 59 mph top speed) I will start by changing plugs first. Should I use Iridium or Platinum plugs ?
Only manufacturer recommended plugs for best performance , It could be you have a bad supercharge , Start by checking your pump and look for a bad wear
ring and impeller most of the time this are the cause of bad performance.
Yep start with plugs and like amigo says manufacturer recommended, need to get those RPMS up to 8000 for top speed so it’s probably not driveline, so plugs, supercharger, intercooler, engine stuff.
