Hum, a fellow 1997 328i'er. Is your car arctic silver by chance? haha
Welcome to United.
As for the ACS Type 3's... a member on the boards (woobie) has them. I've never heard of any problems with them bending very easily... and being ACS, I'd expect top of the line quality. (you get what you pay for, heh)
Congrats on the sub installation, what kinds did you put in? And what kind of box?
Hum, as for making her purr.... if you have no engine mods yet, I'd suggest a Dinan Cold Air Intake (personal preference) and Conforti Shark Injector Software. Together those are usually the first engine mods recommended to people, and the software/chip works well with the intake. If you want sound, get a catback exhaust (i like the uuc system u).
What all have you done to it so far? And again, welcome.