Well for the TB/Plenum I'd say get either a 70mm or 75mm, both will yield about the same power. No reason for a new intake, you can uninstall yours and port match it for a little more of a gain, but as stated, it's not going to do very much.
Headers, get either shorty or long tube (your choice) ceramic coated BBK headers. They are highly rust resistant and will not tarnish like chrome or stainless steel.
Buy the headers from
Mustang Parts & Performance - American Muscle (they're the cheapest I've found), and the plenum kit from
Latemodel Restoration Supply - Mustang Parts, Chevy Truck Parts & Dodge Challenger Parts where they're way cheaper than everbody else.
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Trinity 99 Mustang SVT Cobra 280 rwhp, 290 rwtq
Selena 95 Mustang SVO GT-40 250 rwhp, 275 rwtq (Under Reconstruction)
00 Mustang V6 (sold)
98 Mustang V6 (sold)
