with the price of gas going up...i am wondering if I should be or can be running on 87 or 89. I usually put 91 in my 88 5.0, and have been as long as i have had it. I bought it from my friend and he said he always put 91, so i did the same. It has a stock fuel pump and stock injectors, a 70 mm MAF, stock TB, edelbrock intake, mac cold air, GT 40 heads, e 303 cam, headers. I am not sure what the internals of the engine are or what the effect would be if i put cheaper gas in it, but with the prices of gas I would love to start paying for 87 or 89 instead of 91. what do you guys think??