HELP: Do i just add mufflers or a full cat back exaust?

[1 BLOWN V8]

Hey all I have a 03 cobra and so far added a kenne bell cold air kit. I have called around to a few exaust shops and also performance shops and about all of the said just to switch out the mufflers only. They say that a catback only adds a little extra HP compared to just switching out the mufflers. is the only restriction the mufflers. Cat back runs $400.00 up and thats with me installing it or I can add flowmasters installed for 135.00 or dynomax super turbos or even dynomax ultraflow's installed for 165.00. What do you all think?
On a second note went out with all the mustangs last night about 30 mustangs in all and had a STI sho up with some buddies and who do they go after. Yep me and wanted to run for a $1,000. I just purchased mine 2 weeks ago and still learning to drive it right. Its my 5th mustang and completley the oppiste of all my others. Clutch sucks in a way and also shiffting. Buy the way I didn't race him. It would have been nice to have one of you other fellow cobra's that are modified thier to take him on.
Ken

 

[03yllwguy]

I had weld in mufflers at first and ditched them... felt no power gains... If you get a C/b it will be a few more bucks, but installing it yourself is a breeze... plus you get the cool looking tips of your choice, more power due to larger diameter pipes. And I swear the aftermarket exhaust is much lighter than the stock. If you're looking for power, go catback!

 

[cobra101]

well, so far it's a shutout. 5 for CB and 0 for others. I am deciding between the flowmaster racing catback ($530.00 plus installation), flowmaster american thunder CB, or 3 inch mac CB.

 

[03yllwguy]

$530!!!!! Who quoted you that? That is insane! Especially for a non stainless system. I know for fact summit carries them for around $300 I know a budy with one. And I'm telling the installation is a 30 min to 1 hr driveway install...

 

[vipergts281]

Go with a full Cat-back and install it yourself. The stock pipes on these cars are small.

Btw, are you in Hemet, CA?

 

[Great8]

Go with the cat-back. The stock pipes aren't mandrel bent, therefore they don't flow as well as the aftermarket ones.

 

[1 BLOWN V8]

Originally posted by vipergts281
Go with a full Cat-back and install it yourself. The stock pipes on these cars are small.

Btw, are you in Hemet, CA?

Yes I do. Do you also live in Hemet? Ken

 

[Lthl Venom 03]

well i went from 395rwhp with a maf adaptor and a k&N filter, and welded on series 40 flows, to 402rwhp with a flowmaster american thunder catback and a JLT rai. so the difference between catback and welded on mufflers is not going to be more than 5... probably more like 2 or 3hp. If you're going to buy the weld ons and get something else with the left over money then get the weld ones. But if its just about saving money and you not going use that money on the cobra then just get a catback because you'll want one eventually anyway.

 

[mystic1]

I would say get the MAC or Flow catback and install it yourself. It is very easy it took me maybe 1.5 hours by myself and that was everything from start to finish. Whoever quoted you $530 needs to be beat with a blunt object. Get a catback you won't regret it!!!

 

[Juiced-03]

I made the mistake of starting with mufflers welded in. BIG MISTAKE! No power gains at all and it still sounded too quiet. Do it right the first time and get a catback. Oh, Dynomax sounds like crap on these cars ;-)

 

[crimecrusher]

I got Magnaflow for $360 and put it on myself. Then spent $30 to have a muffler shop fix it.

Muffler swap only would be a good choice for any mustang or non-SC cobra. In the past, the muffler was more to change the sound rather than add power. However, on the '03/04 Cobra it is well documented that a catback adds significant power for the money.

 

[vipergts281]

Originally posted by 1 BLOWN V8
Yes I do. Do you also live in Hemet? Ken

No. My grandmom lives out in Palm Springs and I was in your area one time hiking. I went up into the mountains near Lake Hemet. Beautiful area I must say.

I like the town of Idyllwild as well. Neat little place. I love the whole area.

:beer:

 

[smrtasp]

I haven’t done mine yet, but when I do it will be a 3 inch catback. I was talking to a guy that runs a local muffler shop and he was telling me that 3 inch was too much but if I wanted it, he would do it. I wanted magnaflow so he called them to get pricing and they tell him that 3 inch for our SC cobras is the best way to go. 2.5 inch is good but in their dyno testing, 3 inch was the best. I guess magnaflow is working on a 3 inch kit for our cars. Unfortunately, I didn’t get any HP/TQ numbers out of him between 2.5 and 3 inch so I don’t know how much better it was.

 

[Lthl Venom 03]

There was an article in MM&FF a while back that tested catbacks on '03s and said that they actually lost power going from a 2.5 to a 3"

 

[Zinc03Cobra]

catback.. Juiced 03 was wise in telling me to get a catback instead of weld ins.. I can't thank him enough

 

[69gt4speed]

It's a easy driveway install for the catback, I have taken mine off and on several times, got a high priced bassani though s.s. and their hardware is hard to beat, if you plan on taking it on and off.

 

[Pale Snake]

I had magnapacks welded in. I saw no sense in replacing a completely new exhaust system for 1/4" difference. They were plenty loud/aggressive enough with the stock H to make the welder step back and giggle when we fired her up. I dyno'd with only mufflers and K&N drop in @ 411RWHP/384fttq. Just my experience. Total cost $ 125.00.

 

[Dominick32]

Why screw up a perfectly stock muffler system.
You dont know this but the factory stock cobra catback system goes for a shit load of money if you ever wanted to replace it.

Buy an aftermarket catback system, SWAP THE PIPES, SAVE THE STOCK COBRA PIPES. DONE!!

If you ever sell the car(or sell it back to the dealer), bring it back to stock with the pipes.

This is just what I would do.

Dom

 

[bones]

Well, I guess I come in on the side of the decided minority but I tend to agree with PaleSnake and SvTang03. I checked out two local muffler shops that both do performance exhaust and Flowmaster's tech line (I had already decided on Flowmaster based on past experience).

The two muffler shops basically told me that there wouldn't be much difference between weld in 2.25" Flows and a full 2.5" cat back. As one said "you're trying to split hairs with an axe".

Both these guys stood to make more $ by installing a cat back but that's what they said.

Flowmaster quoted the following typical #'s for the 03 Cobra:
2.25" weld in Delta 40 2-chambers with stock pipes, 5-7% gain.

2.5" American Thunder cat back, 7-10% gain.

Assuming it's your first mod and you have a conservative 365 rwhp to start that gives you 22 HP gain for mufflers alone and 31 HP gain for cat back (using 6% for muffler and 8.5% for cat back) or 9 HP difference (Real world may be closer to SvTang03's #'s.

Just for kicks I went to the Stangnet calculator (I know, there are lots of other factors involved) to see what theorectical ET difference there is between 387 HP and 396 HP for a 3865 lb car (200 lb driver). It's one tenth of a second for a mid 12 ET. If that's important to you go with the cat back. For most of us with daily drivers and occasional to rare track use the ass-o-meter is not going to feel the difference. IMO bang for the buck goes to weld ins.

 

[Phxcobra]

Go to a performance shop and get a custom exhaust. I was quoted appr. $450 for x- pipe all the way back without cats. Doing that with aftermarket parts, you're looking at 900 for xpipe and catback.