Im from cali so I use the 91 octane. I just found a place that has 101 for only about a dollar more per gallon. I have already been tuned on 91 octane and have been running that (runs strong). If I were to just use 101 now and then would I be looking at much of a gain without a tune? What would a safe amount of boost I could run over the standard 21lbs? thanks

 

With no changes, the 101 won't help, but if you turn up the boost 2-3psi, you could mix the 101/91 and have a blast. It's too bad you didn't find the 101 before the custom tune, because you could have gotten tuned on 101 full time. I'd do that for only $1 more per gallon.

 

where is the gas?

 

its right off the 55. 76 station

 

how much boost would be safe to run? 24-25 be ok?

 

I think this is the answer you are looking for...

 

The only other factor is difference in the fuel's specific gravity affecting your AFR. Typically race gas has a lower SG, so it will run a little leaner, which is what you want. But without fuel control to compensate you won't be getting the full benefit. But as an example, when I go to the track and run race gas I lean out from 11:1 to 12.5:1 and add 5-10 degrees of timing, as well as run as much boost as the turbo will make, which is good for 5 mph and 5 tenths, consistently. I'm afraid the boost doesn't help much though, since I'm maxing out the stock turbo on pump gas anyway (42 lbs/min airflow), so the majority of the gain is from the more agressive timing/afr. In your case you owuld benefit by being able to run more boost in the midrange, which will bump up the torque, and really wakes the car up for spirited street driving. If you don't have cams you'll probably hold a little more on the top end too.

 

+1
increased ignition timing will make a noticable difference in power even with the same map. less chance of ECU pulling time. spike boost higher for peak torque.