I have a MY00 Impreza RS (compression 10:1 stock IIRC)

The lower octane I run, the worse ping I get. 87 octane results in an uncontrollable ping driving uphills or when I "give it some gas." 89 is slightly better and I can manage to get up a hill without too much pinging, but only if I do not maintain a speed. I need to accelerate slightly all the way up the hill. 93 even pings slightly, and I used it all last summer. It seems to ping more in the summer than in the winter, but it could also be the case that I don't notice it as much since the windows are up.

I have a CAI(Ganzflow with Amsoil filter), magnecore wires, NGK Iridium plugs (installed at 18K) and replaced the fuel filter at 43K miles. I do clean the Amsoil filter at least once a year (3 weeks ago).

Forgot to mention I'm almost at 50k miles currently.

Any ideas or suggestions would be appreciated.

 

Sorry for posting in the wrong forum. I posted there because I was reading the thread (gas difference) and they started discussing detonation issues.

I'm sure they are the right plugs, I bought them as part of a GB back in the day. I was the original silversuby on i-club.

A couple times a year I add a fuel additive, last fill up I tried Marvel Mystery Oil at a friends recommendation.

The Ganzflow intake uses the stock box, just replaces all of the plastic "piping" and the reservoir with a aluminum pipe that runs into the fender. The Amsoil filter is the stock size, in the stock box.

I will try downgrading to the NGK Coppers to see if that helps around 50K. I would expect a lot more drivers to being having similar issues if that's the case because I did buy them with a GB(group buy).