L99,gear swap..does or will it need a Retune?
 

I have a 3200stall on factory gears..curious if i need a retune for each shift point or just a speed recalibrate

Retune

For each shift point?

With a stall and gears you need to retune for sure.

When you enter the new gear info it will update all your shift mphs. The rpm should shift points would stay the same.



If you don't update your tune your speedo will be off which can add mileage to your car faster (not cool).



Most tuners (us included) will not charge a full tune rate just to update the gear size. In fact if we have already tuned your car and paid for the vin we would do something like that as a no charge.

If i step up to 391s in my l99 thats already tune for cam and headers my tuner will just readjust the speedo..the gear swap is an input in hp tuners that corrects everything?

Correct

Can this be used after the initial flush of the new gears..cant seem to get a straight answer on the search function.. its ac delco differential with modifier https://www.gmpartsgarage.com/oem-parts/gm-oil-88862624

Yeah that will work fine.