So what's my next step?
 

I have a K&N and some pretty nice flowmasters on my 93 notch automatic. What should my next upgrade be? I am guessing that I should change the gears. What are the best gears for an 93 automatic?

Re: So what's my next step?
 

Your next step should be to post this question in the Windsor Power forum where it belongs.

However, since you're here, I'll reply. :)

Replacing the differential gears is the logical next step. I suggest either 3.73 (minimum) or 4.10 rear gears to compliment your automatic 5.0 Mustang. The actual gears (Ford Racing) are less than $200. Installation costs will vary but figure another $200. - and, for your own peace of mind, plan to have the install done by a pro.

Re: So what's my next step?
 

I figured on 4.10's.

So help a newbie. What do the gears do and how do they help to imprive the performance of the car?

Re: So what's my next step?
 

The differential gears serve to multiply the torque of the engine at the rear wheels, meaning that, with traction, you get out of the hole and accelerate faster, usually about a half-second faster after a switch from, say, 3.27 gears (stock) to 4.10's. That means that if your AOD Mustang runs a 15.0 quarter mile, with traction, you could see a 14.5 or close to it. A noticable improvement that you'll be able to feel in the 'seat-of-the-pants dyno'. :)

Of course, if you don't get traction it's a lot easier to do burnouts (and fry your AOD).

Re: So what's my next step?
 

I agree, you should go with the 4.10s. The next step after that is just to continue all of the bolt on aftermarket parts. I'd definitely do your exhaust next. Upgrade to 2.5" h-pipe, and catback system with better flowing mufflers (DynoMax, Bassani, Borla, Flowmaster, etc.). You are going to want to get some headers too. Then a bigger Mass-Air meter, throttle body, EGR spacer & maybe some underdrive pullies. You'll be shocked at the differences all of these mods will make once they are all on your car. Gears will be the best bang for the buck though...by far.

Re: So what's my next step?
 

I agree, 4.10 gears next.

Then I'd throw on a 73mm MAF, a 65mm TB, some headers and a nice H-pipe, and some under-drive pullies

Re: So what's my next step?
 

I've already got some pretty nice Flowmasters on it. I am guessing that I should add X pipes underneath after getting the 4.10's?