The APR "chip" can be purchased in 91 and 93 octane flavors. Here in SW Ohio, the majority of the gas stations (and all of the Shell and BP stations, which is what I generally use) offer 93 as the rating for their Premium fuels.

Yet, some stations still offer 92, and some (not many) only offer 91. Sunoco has 94 if you care to pay through the nose.

My question is this -- if you chipped for 93 (which does provide the maximum of "everything" this 2.0T can offer) and if you are forced to buy 91 or 92 octane, is there any issue with respect to preignition, valve/piston/turbo high-heat, liver damage, dry eyes or early onset scurvy?

In other words, what would be the "safety" advantage, if any, of chipping for 91 when probably 2/3rds of the time, 93 is available? Conversely, what would be the "risk," if any, of chipping for 93 and 1/3rd of the time ending up with less than 93?

Much ado or worth contemplating on the merits?

Signed,

Chicken Guts in Cincinnati

If you get an even-numbered octane just set it to the next setting down. So for example if you get 94 octane set it to the 93 programming, and if you get 92 octane set it to the 91 octane.

I shouldn't imagine you'd have too much trouble, but having that safety net is always a nice thing. Perhaps someone who's much more knowledgeable about this kind of stuff can chime in :D

Your situation seems like the perfect reason to buy multiple programs. I have the fully loaded ECU but I don't think I'll ever switch it out of 91.

Asked a similar question on audizine a while back
http://www.audizine.com/forum/showthread.php?t=301302&highlight=100+octane#post4036481

If I understood Keith's response correctly, combined with the information here
http://stason.org/TULARC/vehicles/gasoline-faq/7-4-What-is-the-effect-of-changing-the-ignition-timing.html

you get up to 2 or 3 octane levels compensation in either direction meaning MAYBE 90-96 octane compensation on 93 program if you consider solely the effects of timing adjustment.
DO NOT quote me on this especially since I don't know the details of exactly how the APR program adjusts and I'm just speculating based on the above online information.
Regardless, there are probably additional changes between 91 and 93 programs else why have two programs if they both allow for 91 and 93 octane?

Personally, I have stock, 91, 93, and 100 APR programs installed so to be safe, I'll just be switching programs based on the gas that gets into the tank.

Asked a similar question on audizine a while back
http://www.audizine.com/forum/showthread.php?t=301302&highlight=100+octane#post4036481

If I understood Keith's response correctly, combined with the information here
http://stason.org/TULARC/vehicles/gasoline-faq/7-4-What-is-the-effect-of-changing-the-ignition-timing.html

you get up to 2 or 3 octane levels compensation in either direction meaning MAYBE 90-96 octane compensation on 93 program if you consider solely the effects of timing adjustment.
DO NOT quote me on this especially since I don't know the details of exactly how the APR program adjusts and I'm just speculating based on the above online information.
Regardless, there are probably additional changes between 91 and 93 programs else why have two programs if they both allow for 91 and 93 octane?

Personally, I have stock, 91, 93, and 100 APR programs installed so to be safe, I'll just be switching programs based on the gas that gets into the tank.

I believe APR would strongly advise you not to use any fuel which does not meet the octane rating for a program.

If you get 92 you would be much better off taking the very minor performance hit of the 91 program (vs the 93) than risk the small chance of something happening to your engine.

Pretty much thinking I would stay "safe" and go with: the Normal (OEM) & APR 91 Octane Programs.

Scott, did you get your A5 chipped yet?

Mark:

I've been using 93 octane chips over the past 10 years in my A4's, and I have never had a problem intermittently using 92 octane fuel. I tend to drive more conservatively when using the lower octane fuel, but I never noticed any knocking or other adverse consequences. I also rarely have a problem finding 93 octane gas here in central Ohio.

I have now been using the new APR 93 chip in my new B8 6MT car over the past 10 days, and I absolutely love it. It is without question the single best improvement that you can make in this car, and an absolute bargain at $600. I cannot wait for the humidity to drop to feel the full effect of this power boost, but it is already very impressive. It absolutely transforms the feel of the car, and I cannot help but think it brings me closer to the feel that I was looking for as I patiently waited for Audi to bring the diesel over in the A4. I see absolutely no downside to this chip, and as I've stated previously, the biggest improvement is how it feels in regular day to day driving. The torque increase is tremendous, and I believe that this chip transforms the A4 from a very good or perhaps even great car, to without question one of the greatest cars currently available. To have this type of performance combined with tremendous fuel efficiency is remarkable. I enthusiastically recommend this improvement to anyone looking for more performance from their A4!

Somewhat on-topic question. I'm trying to figure out pricing for the APR and GIAC chips. The GIAC website mentions nothing about costs, so if someone could enlighten me that would be helpful.

As for APR, it seems it is $600 but then if you want to switch between stock/tuned, it will cost you another $149. So total real cost is $749+tax. Is that correct?

As for APR, it seems it is $600 but then if you want to switch between stock/tuned, it will cost you another $149. So total real cost is $749+tax. Is that correct?

You are correct on the standard APR pricing, but I believe that they have extended the opening sale a bit longer so that the total cost is still $600. Check with your APR dealer or call them directly.

You are correct on the standard APR pricing, but I believe that they have extended the opening sale a bit longer so that the total cost is still $600. Check with your APR dealer or call them directly.
I believe that extension was just for the A5 2.0T.

I believe that extension was just for the A5 2.0T.
No, I recieved the sale pricing on my A4

No, I recieved the sale pricing on my A4

Good. I'll check that out as soon as I actually receive the car next week.

First time I'll have chipped a car but from what I've read it will make a substantial difference.