I went and talked with a local performance shop today about exhaust. He won't install an exhaust without a catalytic converter, but will do a custom setup where i can do a bolt in cat or strait pipe. All his exhaust work uses Mandrel bent tubing just like the ones made by ZZP & Magnaflow, so I'm not exactly sure what option I should go with, and am looking for opinions or comments.

Option 1: 100% Custom with bolt in swappable cat or strait pipe....$700

Option 2: Standard Weld in downpipe, weld in catalytic converter, and welded from cat back. Again all his work is Mandrel bent tubing....$500

Option 3: Bolt on self-installed ZZP Aluminized Cat back Exhaust w/bolt on ZZP downpipe (not sure if I would do cat or offroad) would be willing to bolt on stock if moved to state with emissions/inspections....could always use a Bungee emulator to simulate the O2 sensor too.....$550-650 depending on options.

Question 1: What kind of WHP difference will I see with cat vs. no cat?

Question 2: If I go with option #3 is bolt on worse than welding for some reason? The performance shop seemed proud he welded all his work. Is it possible that it might whistle which is why ZZP sells the ZZP Interlock secton for ZZP downpipe sections

Question 3:This is my family car that I'm just doing light modifications to (exhaust, tune, intake, 3.6 pulley) and I don't want it loud at cruising speeds because we do lots of traveling. I'm sure if I have a catalytic converter it will be plenty quiet at 70-85mph cruising speed correct? If I go without cat, will mufflers be enough? Or would I have to get a resonator?

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2005 GTP
Planned Mods:
1) Wizair CAI
2) TOG Headers
3) 3-inch DP
4) 3.6 SC Pully
4a) Pro Dyno Tune
In that order. 4 & 4a done the same day.

The cat doesn't do much of anything for sound. The catalytic converter is simply an emissions piece. Your stock exhaust is actually pretty beefy for what the car has from the factory, so replacing it isn't necessary if you want to make a quiet, lightly tuned faster family sedan out of it. You already have a resonator that's about 3 feet long (I just patched mine, dumb thing is HUGE). Without a resonator, your exhaust will sound raspy and probably horrible (I weighed the option myself just recently). With one, it's smoother. For what you say you want, your best option is snag some decent headers and forget the exhaust.

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2012 Ford Focus SE Sport
2012 MINI Cooper Clubman

I have ADHD and drive a Focus. Ironically.
Although gold dust is precious, when it gets in your eyes, it obstructs your vision.

I'm not against it being loud when I stand on it, i just don't want lots of cabin noise when cruising down the interstate. As short as the headers are, I don't understand upgrading the headers unless I am making 400-500+HP. Seems like there would not be much restriction there as other places, and doesn't the supercharger just help blow right through the headers? The infamous U-bend has to be deleted, so wouldn't a downpipe be better?

I'm not trying to say you are wrong, just trying to get a better understanding of your point of view. Also thanks for moving my thread.

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2005 GTP
Planned Mods:
1) Wizair CAI
2) TOG Headers
3) 3-inch DP
4) 3.6 SC Pully
4a) Pro Dyno Tune
In that order. 4 & 4a done the same day.

04+ Dont have a U-bend.

Q1: I would go for the hogan performance downpipe for your needs/wants. It has a bolt on cat or straightpipe (http://www.hoganperformance.com/dp13s.htm). You have options this way incase you do ever decide to take it to the track.

Q2: It depends on who does the welding. Welding can cause holes that you can't see if its not done properly causing slight exhaust leaks. Bolt on is a safer bet for the DIY crowd or anyone who might want to change things easily later.

Q3: Its all about personal preferance. For the sound and performace you are trying to achieve, I would go with a glasspack as a resonator to get rid of the high sounds, and some straight through style mufflers. Go on youtube and see what you like. There are a ton of exhaust clips on there.

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What Mike is trying to say is on just about any car, the exhaust manifold in stock form is one of the most restrictive points of an exhaust system. Replacing them with headers will allow the engine to breath a lot better. There's no magical exhaust that will give you tons of extra HP. Power gains will be small at best. Where you could notice a difference is when you go to fill up your tank. Opening up the exhaust will give you better fuel mileage because the engine breathes better, especially if you match it with mods to the intake system.

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98 GTP (RIP 11-5-09); 73 Z28 Camaro (350, TKO 600);01 Monte Carlo SS (L36, L67/L32 hybrid in the future)
"Death smiles at us all; all a man can do is smile back"

In terms of HP, exhaust mods don't give much, but they do allow you to go further modding to gain more HP. Headers will give you MUCH more bang for your buck than a cat back. And supplysgt is right.

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2012 Ford Focus SE Sport
2012 MINI Cooper Clubman

I have ADHD and drive a Focus. Ironically.
Although gold dust is precious, when it gets in your eyes, it obstructs your vision.

My end goal is to have a 4 hour tune at the local dyno. I figure with intake and the right exhaust I could safely put on a 3.6 pulley right before the professional tune on the dyno. I just need to know what that right exhaust would be. Would just headers be enough? Or would I have to replace the whole deal? I'm fairly confident with just a few supporting mods these guys could keep my KR to a minimum. The shop has to be $250,000+ shop, and there are 2 NASCARs sitting in the front lobby. It's a pretty impressive shop.

_________________
2005 GTP
Planned Mods:
1) Wizair CAI
2) TOG Headers
3) 3-inch DP
4) 3.6 SC Pully
4a) Pro Dyno Tune
In that order. 4 & 4a done the same day.

I would go in and ask the shop what they think is best since they will be the ones doing the tuning. Let them know all your options and decide whats going to be best.

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You shouldn't be putting on that 3.6 without headers. As I said, stock exhaust will be JUST fine, so long as you have headers. Then the 3.6 (maybe even 3.5) and some other mods can come into play.

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2012 Ford Focus SE Sport
2012 MINI Cooper Clubman

I have ADHD and drive a Focus. Ironically.
Although gold dust is precious, when it gets in your eyes, it obstructs your vision.

Thanks for all the help everyone. Now I guess the question is which set of headers to get. From the reviews seems like I should go with TOG or ZZP. I read the entire sticky about headers, and some of them have issues with being to close to the radiator fan housing and/or A/C lines. Do either of these sets of headers have similar issues? The sticky does not say one way or another if they do, and I'm curious about an 04+ owners experience with either of these headers.

I used to be a parts changer in the Army so I'm sure i can handle this myself, but a guild/walkthough for header change would be awesome if you know a link. Google didn't turn up much.

_________________
2005 GTP
Planned Mods:
1) Wizair CAI
2) TOG Headers
3) 3-inch DP
4) 3.6 SC Pully
4a) Pro Dyno Tune
In that order. 4 & 4a done the same day.