Join Date: Sep 2006
Location: Las Vegas, Nevada
Only one company makes headers worth having on theses cars they are mid length they require modification of the exhaust cats and back, it's easier just to redo the who damn thing at that point the factory pipe is smaller then the collector anyway.
There are no long tubes that fit the 4.6 thunderbird without steering shaft modifications, a hammer, welder, cut off wheel, and a lot of time/patience.
JBA and SS Autochrome both offer direct fit shorties that replace the factory manifolds with no other modifications but they aren't worth much if any performance gains, they are over priced, and they are known for cracking at the collectors on number 4 primary tubes on the passenger side.
Another option to consider would be having your factory cast iron exhaust manifolds ported and ceramic coated by Preston at braincoating. He offers mild and wild port jobs and coating options.
Regardless of what you choose grab some Percy's dead soft copper gaskets and stage 8 locking header bolts along with a decent set of highflow cats, from that back along with the header/manifold of your choice any decent exhaust shop should be able to fab you up a nice true dual exhaust system or check out mandrel bends exhaust kits for the tbirds.
Hope this was helpful. Anything else try searching the exhaust forum.
-1996 Pearl White Thunderbird 4.6 Sport 4v with many mods:
Current Best: 13.583 @ 103.74 10/2014.
227hp/241tq measured on calibrated mustang dyno, tested at full vehicle simulation with inertia enabled, no number skewing.
-2001 White Ford F-250 Super Duty 6.8 V10, 4-door, 4x4, Limo Tint, BFG KO2's, Bilstein 7100 Remote Reservoir Race Bypass Shocks, 6" Spring lift, Kenwood Double Din, K&N Intake, FlowMaster Exhaust
Amber_Murder's Daily Driver.
-2005 White GMC Sierra 3500 6.6 Duramax, Dually, 4-door, 4x4, Limo Tint, BFG Commercial T/A's, Rancho RS9000XL Shocks, Kenwood Double Din, K&N Intake, Banks Monster Exhaust
Chris_Murder's Daily Driver.