Bottlenecks in a stock GT


New Member
May 24, 2004
I've been trying to figure out what mod to do next my 01 GT (not that I've done a whole lot to it anyway -see sig), and I'd like to go with something for performance rather than appearance. I'm a poor college student so I don't have a lot of money (going to have to stay n/a for now). I'm curious from people who know the car a little better than I do :hail2: what the bottlenecks are, what the restrictive components are on a stock GT where there is a lot of potential for improvement. Hypothetically, for example, if the throttle body is restrictive, then it might do me some good to get a better one, whereas if the stock air intake is pretty good, going with an aftermarket CAI is pretty worthless. That's the kind of information I'm looking for.

I know a lot of people highly recommend underdrive pulleys to regain horsepower from accesories. Does anyone know what all of the accessories are that run on pulleys? The only one I know of for sure is the water pump pulley, because Steeda points out that the design of that pulley changed in the middle of my year. Also, has anyone noticed adverse effects of reducing the power to the accessories using underdrive pulleys that would for some reason not make it worth it, or is the reduction pretty safe and adversely unnoticable?

Anyway, I'm open to suggestions. Thanks!
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Well, this all depends on how far you want to go.

Our exhaust sucks, from the headers on back so, that's something you could look at. Our intakes aren't as bad as a lot of people make them out to be but, if you do the exhaust, dont forget to do at least the plenum/tb. Our stock gears don't really do our cars justice, although, if you like to drive at unusually high speeds then, gears aren't for you. If you like to take stuff off the line and kill some folks randomly, 4.10's will be your friend. But at that point, traction becomes an issue, a good set of drag radials will help you regain that lost traction.

Other than that, it's a lot of little tinkering based on whatever you want to do. Those few things up there are some of the only major set backs for us stock. Sure, there's more but, once again it all depends on how far you want to go.
First thing you should do is gears and get the speedo corrected. That will give you more SOTP feeling than anything else short of power adders.

Gears, mid pipe, timing adjuster, plenum, pullies. The other stuff like suspension could come after.
Gears are going to be the biggest bang for the buck (especially on a budget) hp but you'll get going a lot quicker. Probably about $500 including install and another $100 or so to get the speedcal.

If you're interested in where the bottlenecks are from the factory, they exist throughout the breathing system...intake/Mass-air, tb, plenum, heads, headers, midpipe, and cat-back. The problem is that until you replace all of them the significance of your gains isn't going to be all that will be right around 300rwhp even with all this stuff on it.

A lot of guys swear by the pulleys but I personally can't risk it with all the electrical that I'm running for my stereo, and it doesn't really "free-up" all that much power when you compare it to other things that you could be doing.

Other things that you should be thinking about/researching:
Programmer (Superchips or Diablosport) - if you get this you won't need the speedcal for your gears
you will find most people say gears (4.10s are popular for n/a) and short shifter shoud be the first mods. i ordered my 4.10s and short shifter (i got a tri-ax), just waiting to install the gears and for the shifter to arrive. (ordered that a month ago through stangnet, i think i better see whats up)

EDIT: also, from what i have read here, for the money CAI's arent worth it for the few hp most pick up. if you have a supercharger that would make the most sense i think because you're pulling in more air (correct me if i'm wrong here). if you are on a budget i would stay away from the CAI for a while and go with gears, shifter, and exhaust. I have heard people go back and forth on headers however. Some say that the stock ones arent that restrictive and that aftermarket headers arent worth the money or HASSLE to put them on. Others say they are. i have yet to get a straight answer on this. I do know that the exhaust manifolds on the 98 and older GTs are very restrictive but i think they changed those on the 99 and up models. ***Someone clarify here if i am wrong***
I hope this helps!
fellamansteve said:
Reaching power band faster = great as far as I'm concerned. Any idea how much 4.10s affect gas mileage, specifically cruising down the highway in 5th? Just curious.

The 4.10 gears will probably cost you 2 mpg, although some people have reported gains in gas mileage. After the gears, I would focus on inexpensive mods like a K & N air filter ($50) to free up the intake and an o/r x-pipe ($200) to free up the exhaust. I would follow this up by replacing the tb/plenum ($400). Some people will recommend a new catback exhaust but the gain is more in sound than actual performance. There are more expensive mods (e.g., LT headers) but this is a good start in helping your stang to breathe better. And with the additional 20 rwhp and the lower gears, you will enjoy a noticable difference in acceleration.
Well I have to agree with the others GEARS are definently the way to go. And as far as the gas mileage it isn't that bad but hey you have a mustang with a V-8, and you wanna go fast. So what do you expect, if you are worried about everyday driving by a beater for $300 bucks thas what I did and park the stang in order to take the time to work on her. If you don't want to spend the money then sell the car and save up FOR A WHILE and buy one thats already fast. Not to sound ignorant but what do you expect.
Follow the general consensus here with gears and a shifter.

As far as intake/exhaust go we don't have significant bottle necks, not like a lot of other cars that DO see good gains from intake/exhaust mods(LS1 cars). Your best bet money/performance wise is to just swap in a K&N, Kool Blue, whatever aftermarket filter and then switch out the factory 4 cat mid-pipe for an off-road version. Cost=$200(o/r pipe)+$50(filter)=$250..... You'll get your best gains there, and you will see gains if you do headers, cat-back, intake,plenum, cai... but they won't be significant and they will end up costing you up to $2000.~which is almost supercharger territory.

Also, I'd pass on the timing adjuster. Good for a little power, but then you have to use premium, and I doubt you want to do that on a college budget.

Lastly, save up and get a good nitrous system if you need real power.
you will get bad gas mileage, because you wont be able to keep your foot out of it. After the newness of the gears wear off it may not be too bad. My first half tank with the gears in I got like 85 miles! I had my foot in it quite often. Its doing better now I use 5th gear more now. It will be fine but when you get into it now it really sucks down the gas.
Phoenix00GT said:
If you're interested in where the bottlenecks are from the factory, they exist throughout the breathing system...intake/Mass-air, tb, plenum, heads, headers, midpipe, and cat-back.
For the record, the breathing side isn't as restrictive as you make it out to be. With typical bolt ons, there is absolutely nothing wrong with the OEM MAF. And the TB isn't very restrictive either. The rubber tube from the MAF to the TB sucks, however. And the plenum has room for improvement. The exhaust side is definately more restrictive than the intake (not comparing the heads though, which is a whole 'nother discussion).
I'd recommend working the exhaust from back to front (catback first), gears, shifter as the first mods. :nice:
I called my local Ford Service Center to find out about the speedo calibration after putting in 4.10s and when he quoted me the price, he was telling me that the engine would be turning about 3500 RPMs at 50mph in 5th and that's why I got concerned about gas mileage. If it's only 2 mpg lost, I could live with that. After all is said and done though, the whole operation sounds expensive. I'm still up in the air, though.

I probably won't race it on a track too much. My basic concern is, coming back to the college student thing, being able to beat everyone else in town driving a ricer. Stock, I've probably got at least 90% of the people beat because it's Iowa and if you have a fart cannon, CAI, window tint, alteezas, and a aluminum park bench wing, you've got a fast Honda. I just want to edge my way up the other 10% and I could get most of the way up with the right direction and some $$$. I'm not too worried about the other American muscle cars, students, most can only afford a v6 stang or camero or firebird and after student loan debt, there's no money left to do anything to them. Unless their daddy bought their car for them, then they're driving a Lexus.
kurst said:
3500rpm at 50mph in 5th gear? nah ah, im not sure of the exact rpm you will be turning but it won't even be close to that.

I'd guess about 80-85mph at 3500 in 5th gear.
:stupid: I don't know why Ford told you that - that's way wrong. 5th gear is big time overdrive. This is how you'll salvage your gas mileage with shorter gears.
Gears are the biggest bang for the buck. The best mod I've done, by far.
The real bottlenecks are the heads, cams, intake (the manifold, not that stupid pipe before the throttle body), and headers. They cost a lot of money to upgrade. Might not be what you want to hear, but don't bother dicking around with throttle bodies and cold airs.