High compression is already there on the GTS, we're already at an 11.5:1 compression ratio (The nastiest Race-built V8 usually has about 10:1 compression) In fact the 2ZZ has the higest compression of any factory engine, period.
It's like this: When the piston goes down in the bore, air and fuel are sucked in, when the piston moves toward the head, all that air and fuel is compressed, at the peak of the "compression" stroke, the spark plug ignites the mess and sends the piston flying back down the bore with incredible force... "So what?" you ask.
An engine's compression ratio is a numeric representation of how much the air/fuel mixture is compressed, the more pressure the mixture is under, the more force will be produced when ignited. In the 2zz engine, the full volume of air and fuel in the cylinder takes up 11.5 times more space than when it's compressed at the top of it's stroke, in other words, it's under pressure cooker-type strains.
BTW, Higer octane fuels burn slower, not faster than lower octane fuels. if the fuel has too low an octane rating, the fuel will detonate from the pressure before the spark will ignite it. this is known as detonation. Therefore, you need a more stable, slower burning fuel in a high compression motor.
forced induction requires lower compression ratios for the same reason above, adding a thicker, copper head gasket, or putting in dished, 1zz pistons will lower the compression ratio anywhere from 11 to 10:1 compression.