Im running the 93 oct. Giac X file on 91 fuel, because its the highest grade gas we get out here in cali[:@] and basically they **** in our gas out here... I was told by my local retailer that the X chip has some sort of varible timming thing??? So basically im not hurting my car in any way because the 2001 a4's also have anti-knock sensors.. But thats besides the point.. Would I see a difference in power if I got the 91 oct. program and used 91 oct. vs. keep doing what im doing and using 93 program with 91?

TIA