03 Cobra exhaust upgrade HELP!!!!!!

JMetro64 · Aug 7, 2009

I recently purchased a 2003 mustang cobra with a few mods, and would like to upgrade the exhaust. The car pulled 480rwhp and 470rwtq. it currently has a mac o/r h pipe and a 2.5" mac catback. I do need cats for i live in vermont and need them for our state inspection. There are 2 exhaust combinations i have been thinking of getting. Either Kooks 1 3/4" long tube headers with a kooks 3" catted X pipe, with a Mac 3" catback. Or SLP 1 3/4" long tubes headers with an SLP 2.5" catted X pipe, and a Mac 3" catback. i am not sure if i would lose torque from the 3" x pipe because of the decrease in back pressure. I am trying to get the most performance that i can out of an exhaust combo so if any of you mustang experts out there could give me some advice on my issue it would be greatly appreciated.
-James

tag4car · Aug 8, 2009

if it helps YouTube - M4H00056 you could always have a set of high flow cats welded inline to the chamber

VEE EIGHT · Aug 8, 2009

You don't have to worry about backpressure when you're run a forced induction setup. FI totally eliminates the concept of backpressure.

cronin49 · Aug 8, 2009

I know that the '03-'04 Cobra's were underated by Ford at 390 hp, but I would like to know where did you get all that hp from a couple simple mods?? 480 hp at the wheels??? That's nearly 560 hp at the motor. I don't think Ford underated them by 170 hp. Most stock Cobra's dyno at around 360-370 at the wheels, so they probably put out about 425 at the motor. No disrespect mister, but help me out here.

joshjwc9 · Aug 8, 2009

It might be pullied, we do not know, but I wouldn't jump to conclusions since he is only talking about exhaust, and not other engine mods.

JMetro64 · Aug 8, 2009

it is not stock. i am not certain everything that has been done to it since i am currently in mass. and all the paper work is in a folder at my home in vt. but what i do know is it has a stage 5 port. 2.8 upper, 63lb injectors, mac o/r h pipe and mac catback. custom Sct tune, sct intake. it pulled 480hp at the wheels and 470tq at the wheels. all the work is done at quinton brothers motorsports in vermont.

cronin49 · Aug 9, 2009

JMetro64 said:
it is not stock. i am not certain everything that has been done to it since i am currently in mass. and all the paper work is in a folder at my home in vt. but what i do know is it has a stage 5 port. 2.8 upper, 63lb injectors, mac o/r h pipe and mac catback. custom Sct tune, sct intake. it pulled 480hp at the wheels and 470tq at the wheels. all the work is done at quinton brothers motorsports in vermont.

OK, sorry, that helps in explaining it.... you got yourself a beast my friend. She should run deep into the 11's. Either combo is fine, backpressure is a non issue when your blown.

JMetro64 · Aug 9, 2009

do you know of any other exhaust combo that could possibly allow me to make more of a hp gain than the two combos i mentioned?

COBRA90GT · Aug 9, 2009

JMetro64 said:
do you know of any other exhaust combo that could possibly allow me to make more of a hp gain than the two combos i mentioned?

Don't take this the wrong way, but you're not going to experience any real significant horsepower differences between all of the other numerous aftermarket exhaust combinations that exist out there once you have replaced your factory exhaust system.

Again, it's worth repeating - significant horsepower differences. You may see a 5 hp gain here with one brand or a 5 hp loss there with a different brand when comparing aftermarket exhaust vendors. Make sense?

Once you replace the factory exhaust system, you have already yielded the biggest exhaust system horsepower gains (due to the restrictive factory exhaust system's smaller diamater piping, catalytic converters, mufflers, etc).

However, there are a couple of factors that you could still play around with though (depends on your setup/car purpose, ie - strip only, race track car, etc):

You can tweak the diameter of your exhaust plumbing (2.5" or 3" seem to be the popular choices) and the style of mufflers you run, ie - straight through (ex: Magnaflow, Bassani, etc) or chambered (ex: Flowmaster). Straight through mufflers are generally less restrictive.

G'luck with your decision, but try to save yourself some grief and avoid making "chess out of checkers," so to speak.

JMetro64 · Aug 9, 2009

ya. price is also an issue. since i am only 19 years old i do not have too much money to spend especially with car payments. I am looking for a 3" catted X-pipe that would fit a 3" Mac catback and with the much cheaper hooker headers. Also How are Flowtech long tubes? i see them for only $299, there must be a reason for them being so cheap

JMetro64 · Aug 17, 2009

i was thinking of BBK lt's SLP catted x and a mac 3" catback. would this setup fit together?

peepeeskillz · Aug 17, 2009

JMetro64 said:
i was thinking of BBK lt's SLP catted x and a mac 3" catback. would this setup fit together?

i dont think so i don't know about cobra exhaust but i know for a gt slp and bbk LT's and mid-pipes have different flanges

JMetro64 · Aug 18, 2009

What catback do u think would be a louder? A Mac 3" catback or a Borla stinger catback?

Nutty 5.o · Aug 23, 2009

The 3" MAC is louder. Stay away from the headers unless you go Whipple or Kenne Bell blower. The lt's will give you some power, but the car should be re-tuned and then you got more money to spend. Get yourself the cat pipe of your choice with the 3" Mac.

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