I have an 05 Aveo and just put in an AEM cold air intake. I did notice a slight increase in acceleration and I'm overall pleased with the CIA. Is a new muffler the next step to increasing engine performance? For $125 I could get a Flowmaster 60 series delta flow muffler. Is it worth it? Is there a better muffler for a reasonable price (under $200)? Also, what are other steps to increasing HP and roughly what would I be looking at cost wise?

Thank you for any assistance!