I Got bored, made some audio clips...Enjoy
1988 Toyota Supra Turbo
HKS SMF Intake
HKS Super Sequential Blow Off Valve (this is what you're hearing)
HKS Type 0 Turbo Timer
HKS Boost Gauge
HKS Sticker (+30 rwhp) [It's the white spot under the spoiler on the window]
Generic A/F Gauge
KYB Struts (Front 2, Stiffer)
Tokico Illumina II (Rear 2, 3settings adjustable)
Front Strut Tower Bar
New 8.5mm Plug Wires
Bosch Platinums gapped to .28
Head Machined down by .04
New Toyota Head Gasket
ARP Head Studs @ 80ft/lbs
ApexI AVC-R Electronic Boost Controller
ApexI S-AFC 2 (USDM)
Full 3" Custom Exhaust
Flowmaster Exhaust (3" in, 3" out)
SupraSport.com 3" Turbo Elbow
More about my car and/or its pieces can be found here

All Runs were done @ 10PSI @ 5280ft Altitude.
Sounds were recorded by a microphone, plugged into a laptop in the passenger seat.
Microphone locations were here: (1,2,3 indicates audio clip number)

#1 Starting the Car, and the first BOV Blast. [217kb]
Frequency Analysis of the First Clip.

#2 BOV Blasts GALORE[865kb]
Frequency Analysis of the second Clip.

#3 My Exhaust Rumble [384kb]
Frequency Analysis of the third Clip.