I wanted to beef up my 99 Merc, just curious of all compatible performance parts for the 4.6 V8 2V. Are there any Mustang GT bolt ons that will work or where do I need to look for performance? If you have any links, please feel free to share or point me in the right direction to getting top power and torque out of this engine.

 

You can bolt on stuff 'til hell freezes over -- you won't get far without spending hundreds (maybe thousands) of your hard-earned cash.
Not gonna go very fast in your 2-ton Grand Marquis.
You are limited on the amount of air flow thru the system -- 65 mm Throttle Body and Single Exhaust are main culprits.
AVOID the use of Throttle Body Spacers -- They DON'T WORK on the fuel-injected 4.6 engine.
To improve intake air flow, remove the "snorkle" from the stock air box, and add a piece of clothes-dryer hose to run forward,
where it will pick up the coolest air from forward of the engine bay. Photo below.
I choose K&N Air Filters, because they are the ONLY Hi-Performance air filters that will work when WET.
Driving at high speeds in pouring rain CAN soak a paper filter, but not a K&N.
Some users of K&N Air Filters complain of problems with the MAF Sensor -- when in doubt, go with the stock Motorcraft air filter, and change it YEARLY.
Dual Exhaust -- adds 20-24 horsepower with 2" O.D. pipes. Larger diameter pipes will DECREASE low-and mid-range torque.
Walker H-Pipe; MagnaFlow 2" x 21" x 3.5" Glasspacks; Walker Tailpipes -- Maximum flow; Pleasant, powerful tone; no droning at freeway speeds.
B&M Shift Improver Kit -- quicker, firmer shifts, less lag -- no fuel mileage penalty.
The '99 Grand Marquis spark plugs = Bosch #9606 -- Double Iridium spark plugs, gapped @ .054".
To avoid many "mystery problems", use the stock, 195-degree Thermostat ONLY -- even in the desert !

Walker H-Pipe; MagnaFlow 2" Glasspacks; Walker Tailpipes.

Custom Dual Exhaust Exits; Superior Tips

Snorkel Removed -- Cold Air Ducted From Forward of Engine Bay.

 

You have to look at the economic part of this. These are great cars but they are a "dime a dozen" and to put big $$ into a 21 year old sedan to make it go faster, that is worth a couple grand at best, needs to sit down and do some hard thinking. Want to go fast, get that Mustang GT. You will be much farther ahead.