Upgrading from NGK BPR9ES from BPR6ES.

[Shane@DBPerformance]

It will be more prone to fouling out the plugs, starting can be harder, more likely to misfire, possible loss of power, part throttle drivability could be worse, gas milage could go down a tiny bit. Or you might not notice anything. 9s are a very cold plugs though, the main problem would be them being prone to fouling out. Most people run 7s on DSMs, you normally wouldn't run 9s unless your running 40+psi and make over 700whp.