I have a magnacharger and Tbyrne says that with their 1lbs of boost increase pulley you dont need a retune. But with any more of an increase you gonna have to get a retune. What gets retuned? A/F ratio? Timing? Both? Everything?

 

You'd probably get fuel trims and timing retuned at least... not sure if anything else would get tuned? Maybe some changes to various parameters to reduce/remove certain kinds of DIC codes.

 

I am not an expert but, I agree you should be good to go without tuning,
here's something to consider:

raising the boost will not affect your closed loop operation, if I remember correctly the stock open loop begins at 64% and some of the magnachargers have changed this to as low as 28% throttle position. Boost will engage around 40% throttle.

I assume that you have the stock exhaust so there is no complication there.

If you were tuned with 42# injectors then you are ok, the 39#ers may be a little small if your MAF gets over 400gm/cyl, check the injector duty cycle with EFI_Live and you will know for sure. injectors can be added any time, if you hear knock at >5500rpm then this may indicate this condition.

The magnacharger belt may slip with the additional force, this may sound like detonation at rev limit, it is very easy to tighten.

If you have headers and exhaust that were tuned with the install then you should be fine otherwise you are mostlikely rich and need a tune anyway.

With additional boost the Air Fuel Ratio is guessing so to be sure that car is not leaning out some logging should be done just to be safe. Changes to Timing should not be required.

however you should confirm these suggestions.

 

thank you guys for the pointers