I will be purchasing a used Mustang GT in the near future, probably a '99-'01 automatic. I have no experience with car modding, but I would like to start modding my car.

The main thing I want to do is add horsepower and increase my car's performance. I don't plan on racing it on a track or anything like that, but I would still like to have the extra HP just in case I ever need it. My goal is to get the stock GT to around 350 HP or more if possible. Right now $$$ isn't an issue, I just need some advice on how to go about doing things.

Currently, my plan is to add the following parts to my Mustang:

Steeda Cold Air Intake
Steeda Intake Spacer
Steeda 4.6L Underdrive Pulleys
Accufab 4.6L 2v 70mm Throttle Body & Plenum
Steeda GT Cat-Back Exhaust

I'm also thinking about changing my gears since a lot of people talk about them on these forums. What do they do exactly, and how do they impact my car's performance? Is it worth buying?

I would also like to know your opinions on the following items:

1. ProCharger HO Intercooled Supercharger - will it work with an automatic Mustang? Is this a good mod? Anything I need to consider?
2. Performance automatics - what is it exactly, and is it worth getting for my car?

I know I asked a LOT of questions, but I really appreciate the help!

 

Unless you want one for looks,CAI's are pretty much worthless.You do mention a S/C so it will have it's own intake.Save your money.Intake spacer=about the same,save your money.UDPs are good for a normally aspirated or turbo charged engine but can't be used on a S/C engine because the you don't want to underdrive the S/C.If you plan on going with a S/C get the 75mm T/B and elbow.A cat back exhaust of any kind isn't going to give you much real HP,4-5 maybe.A good exhaust starts at the engine and goes from there.Using an auto trans pretty much limits you to Hooker,Kooks,or Bassani mid-length headers.These,I think,are the only ones that will clear the auto trans.A manual trans gives you more choices,but the forementioned ones will allow removal and replacement of the transmission with out removing the headers.When you go to install the headers you'll see what I mean.Gears allow the engine to rev faster.This makes the car think it weighs less with say 4:10's than it would with stock gears(3:27's).Gears raise the RPM's at all road speeds.Some people don't mind and some people do.It usually has to do with exhaust noise at highway speeds.Gears really improve acceleration and don't hurt top end.Supercharger brand pro's and con's are going to be a personal preference as far as where the power comes on,ease of installation,and costs.A shift improver is always a good addition to any automatic tranny.Yes they will work with a S/C and it would be adviseable.You can get a shift improver that changes the passages in the valve body physically or with a programmer that changes them inside the Engine Control Module (ECM).BTW there is a lot of snake oil out there so check things out that you don't know about here on these forums.We'll try to help as much as we can.The only stupid question is the one you didn't ask and ends up costing $$$$$.Welcome.

 

What Chopper said.
your not gonna get 350 out of it with just minor bolt ons. supercharger/blower with a complete exhaust and a good dyno tune.

 

1,2 and 4 won't really do squat until you open the heads up.
3 is worth doing unless you drive in cold weather or have a loud stereo...the 5 hp is NOT worth the super low charging power of your alt.

5 is definitely worth it just for the what it will sound like now.

6 is the most effective way to make your car faster w/ nothing more to do...(like fill your nitrous bottle or rebuild your blower)

A. is good to go, and yes can use on an auto, nitrous is cheaper and you don't need to rebuild, but yes you need to fill the bottle after every 8-10 runs if your spraying 100 hp

B MOST definitely you need tranny enhancement...lentech is better than performance automatic....and ford makes crappy auto's other than a c4 or c6 they are heavy and power robbing, and weak as hell

My suggestion to start off......do a set of lower control arms, the exhaust, 4.10 gears, cheater slicks, 3000 stall converter, shift kit then go practice a lot at the track......i'm sure you came up w/ your 350 hp by how fast you want ET to be....gearing and traction makes up for ALOT of hp

just what i mentioned can get you in the mid 13's spray 100 shot and you should be making about 325 hp and running mid to hi 12's

that car is heavy and needs a boatload of gearing......less than 4.10 you will be a VERY SAD boy at the track

 

Thanks for the advice so far.

From what I understand, my best bet would be to install a supercharger and change the exhaust, gears and the transmission. I don't know the differences between headers, so can you explain that to me?
I'm guessing that I can add any kind of exhaust, but the headers need to be a certain type?

I checked out the Lentech website and picked out these transmission parts... what do you think?

1. Street Terminator AOD transmission & valve body
2. 12" Super Street convertor
3. Stage 1 Input Shaft

Are these things I can install myself or would it be better to take them into a shop?

 

What's wrong with underdrive pulleys in cold weather? Or even hot weather for that matter?

 

UDs are a nono period if he plans on getting that procharger. as is a CAI.

 

Headers are marketed by the length of the tubes coming out of the exhaust ports.There are shorties,equal length shorties,mid-length,and long tubes.Shorties are mostly stock manifold replacements and are good for maybe 2-5 HP.Shorties are also 50 state legal.Some companies swear that their shorties make power equal to long tubes (JBA) but since I have never seen a test on these I can't comment.Bassani makes the only set of mid-length headers that I know of.These require their own Bassani X-pipe.They come with or without cats.Acccording to Muscle Mustangs&Fast Fords they made 17.4 hp and 17.3 ft/lbs of torque.I have a Bassani exhaust on my car and the fit and finish is excellent.They are also 50 state legal.Long tubes give the biggest gains as far as HP.You can expect 20-25 hp over stock.You must have a special X or H pipe to match up to the the rest of the exhaust but the one you have can be modified by an exhaust shop to fit the headers.You also need Malfunction Indicator Light (MIL) eliminators or a handheld tuner or you will have the CEL lit on the dash.They are not 50 state legal.Unless you have time to learn,have the transmission work done by a reputable shop.The valve body replacement is no big deal but to go any futher can be a disaster.

 

i have a blower on my mustang i curently use a pxton novi2k its a bad *** blower but remember you go wit blower or turbos you will need other stuff for it to work properly and not have problems

 

actually the 4r70w auto tranny is a pretty strong tranny, and I think the 99-04's all have it. it will hold 350HP without breaking apart (I believe around 400HP is about the breaking point). I've heard around the grapevine that a shift kit will burn out your O/D gear (I don't remember the reason why, and I'm not 100% sure if it's true or not), but there are people on this site with shift kits and a working o/d. You can get a tuner that will firm up your shifts and adjust your shift points so the auto isn't such a slug, and since you want gears, it'll kill two birds with one stone by allowing you to change your speedometer. The 4r70w is a much better tranny than anything else ford ever made before.