The only two bolt-on mods (non-invasive) that I know of that will increase the sound of the turbo spooling in the cabin are:
1. Larger intake (sounds like you already did this)
2. Better-flowing cat directly downstream of the turbo (a high-flow cat is better than a test pipe, since test pipes stink and will likely pee off those behind your parked near you).
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The location of the turbo, routing of the exhaust and intake, as well as the firewall will all change what you hear from the engine compartment.
I heard a bit of spool in my previous STI, but it really came alive after installing an AEM CAI. I wasn't a huge fan of the added wooshing noise and BOV sound when the BPV relieved intake pressure, but it was worth it, since Cobb showed some modest power gains with its OTS tune.
I purchased a high-flow, catted-DP, but was hit and eventually got rid of the STI before I could install it.