All thigs being equal, the 87 oct. will make MORE power than 93 oct, just for the record.
As for modding Saturns, if you can make it happen, more power to you. Speaking of modding 4 bangers-Will it cost you more money than say, a DSM? Yes. As much as a fast Honda (which is rediculous)? Porbably more. WIll it be cool and different? Obviously.
Mustangs, camaros, and Mustangs are as bad as Hondas now adays. No matter what whacky motor, or mod you put in/on it, it will be unoriginal, and done befor, maybe 1000's of times. I would hate to go to a meet, or be online and see 5 poeple with my same freaking car. I can walk up to any of the above said cars and (to a point) know what it will ET. and trap. What is the fun in that? A fucking t-70 fox body is played out now adays!
There will be haters no matter what you choose to do, period. If your motivated, make it happen.
As for whats fast- let me look in my black book.
0-100mph:if your not NA or slower than stock kill yourself
100-110: respectable 4-6cyl, better have no power adders if your a v8.
110-120: Quick, will win most of the races you get in to.
120-130: Fast street car, probably the shit in your area,and have some nutswingers
130+ : The Elite. Beat bikes, hurt egos, take that money meing. .01% of car
enthusiest
Bikes-Traps slower than 130, its not worth riding, and I dont give a shit how well it
turns.