Welcome to the XOC

I don't think you can expect much from a change in gasolines. Clean your MAF sensor, drop-in a K&N filter and that should get you 8 - 10 more hp (so they claim).

I have an '04 SE S/C and if you are unhappy with the lack of kick by the supe than you should drive a 1st gen without one. That's a big strike against the 1st gens is they are underpowered. But I still wouldn't trade mine for anything. I didn't buy it to race. I bought it to get me where my civic couldn't and it does that well beyond my expectations.

Take care of it with the routine maintenance and it will last you as long as you want it to.