B18C injectors are very loud...sometimes they seem even louder than normal. Mine do...at 132k miles...and they did at 80k as well. Get some Regane in your next tank, and see how they do then. But just remember, they are loud.

Upgrading? Can't hurt...but that's only needed if you plan on doing some big engine work. Suggestions: that's a bit different. I know some people use DSM injectors, others use Prelude, and some find some good aftermarket ones.

For now, you should be fine. Are you having a colored exhaust? Is the header/intake stock or not? If you have a header on there, they will sound louder due to resonance.