When modifying your 2003-2005 Dodge SRT-4 and 2008-2010 Dodge Caliber SRT-4, you need to not forget one major part of the fuel/air/ignition mix..
We hear from a lot of customers that bump up boost with the Diablosport tuner, but do not change their spark plugs, and then they have misfiring and hesitation. Why? Well, once you have more boost, you have higher heat, and you need spark plugs that can handle the pressure.
The NGK Iridium plugs are fantastic for the SRT-4.
Now onto the second part of this important topic.. Heat ranges!
A spark plug that works well with 10 psi, wont work very well with 20 psi.
So, its important to keep in mind heat ranges when choosing plugs.
If you are increasing power by about 30-85 horsepower you should go with one range colder plugs.
If you are increasing power by roughly 100 horsepower or more then you should go with two range colder plugs.
Check out the range of NGK Iridium plugs ModernPerformance.com has here: