Emissons??
 

280 KM on a 5.0L
advanced Timming
Cold air intake
Flowmasters.
runs very very good
what else can I do that would help.
i've been told to run high octane befour and give them the car real hot.

I'd retard the timing back to stock setting, at least. When you advance the timing, you're increasing cylinder pressure, which creates oxides of nitrogen due to higher peak combustion temperature. EGR can compensate somewhat, but you're safest going back to 10 degrees BTDC.

You may want to skip the high octane because it burns slower, and use that cash on a couple of bottles of Emissions Cure they sell at parts stores. That stuff is supposed to work pretty well, and you just dump it in the gas tank. Make sure your PCV valve and air filter are in top shape, too.

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Capri306, Moderator, The Mustang Works Online
1979 Mercury Capri, 5.0L -- C4 -- 2.73
1987 Mustang LX Notch