I guess that depends upon how you define power... torque? HP? Both?

Short answer is, I don't think anyone knows for sure if there is a measurable gain running cat-less.

I can tell you this though, if you run without a cat, you'll go deaf! I tried it with a different brand header and a Borla sport exhaust. By 3500 rpm, I swear my ears were bleeding, and every interior body panel was buzzing so loud I thought the car would would fall apart. No kidding. Dead serious.

Good luck!

 

TY for the input and help.

 

Although there is a serious fine for not running a cat. Up to $25K here in Wisconsin!!!

The mini is on the high side of the polluting scale as it is...removing your cat would be a crime against the environment.

 

Uhh....Will someone tie COOP D'ETAT up so his comments dont get out to the world and ruin our fun.

 

I took the picture and it has been pointed out to me that the spring in my installation is too compressed. I wanted to let you all know this to insure that the ball joint works properly in your installation. To be sure that I had the right installation, I called Supersprint and asked them what is the proper set up, did not mentioned what type of header I had installed. I was told that the spring has to be compressed about half way. There should be about an inch of screw after the nut. I am not sure if that is what it will take to have the riight setup in the OBX header, the screws might be shorter.

Bottom line is that the spring needs to be about halfway compressed. I will make this change in my car this weekend. If you do not make this change, you will be putting stress on the screws that the header attaches to at the engine block. After many months of use as it is in the picture, I have not had a problem, but will make the correction now.

Bomboasy

 

Well like duhhh......Defeats the purpose of the spring being in there ...

 

Yes, I know. I feel responsible for having posted the pictures and would not want anyone else making the same mistake. The reason it was installed like this, as I just remembered, is that we had to use a similar dougnut than what should had been provided. The OBX dougnut was missing and we used something similar, so to insure it sealed properly, it was tighten more than the installation required. Again I do not want others to follow my bad example.... I now have the OBX dougnut and will replace it along with the proper setup.

Bomboasy

 

Bomboasy, You’re a conscientious guy in keeping your information straight.

Thanks for that and the feed back.

 

 

Damn this set up is loud!
OBX, Magnaflow cat (good to 390 cu in!), Magnaflow muffler, 2.5" pipe

Too loud. I'll have to get a resonator installed. I did a quick and dirty gTech run, and it showed over 8 hp peak gain, and it was 21 degrees F hotter than this morning..... But take these numbers with a huge grain of salt, I didn't do good baselining after getting the Gtech re-installed after lending it out.

I took a bunch of photos, and will post them as well. The install of the header, all parts and labor came to a total of $775, $600 for the install, and all the hardware today....
SS tubing,
SS U-bend,
Muffler,
SS Tip,
Hangar stuff
Welding
EGT Boss
OBX flange to Magnaflow Cat
Straight pipe to Cat
Pipe to cut bend
Cut bend to cut bend
Cut bend to muffler
Muffler to tip

Shop prices for the tubing and the bend were high compared to the web, but web items charge shipping, and some bits are heavy. The muffler was a good price, as was the tip. Labor was rediculously low, but I'm a buddy, and a good repeat customer.

After all of this, I'm stoked (and will be more so when the car doesn't wake the dead at WOT), but if someone comes out with a 2.5" cat back single side, go with the OBX, either stock or aftermarket cat and that.... It will be cheaper...

Matt

I'll post more details later, I'm wayyy behind on some work things....

Matt

 

Looking forward to it Matt! With my fab exhaust, I decided to go with a resonator also. It took off a couple dbs, and refined the sound just perfectly. But then I didn't touch the header/cat either...

 

just you wait. When I drive to work, open your window. It's only a few streets over, I'm sure you'll hear me!

Matt

 

WFH tomorrow buddy! I really can't drive to work with my suspension situation now...

If you don't have a sound pressure meter, they are pretty cheap at Radio Shack. Sort of fun to see how exhaust modifications make for internal and external audio level changes...

 

I still can't hear you. My ears are still ringing!

Matt

 

We did run into four small problems.

1) The header didn't fit without lowering some of the front clip. Just a little fitment issue getting over the front sway bar.

2) One of the exhaust tubes didn't come out exactly straight. This meant that one of the header bolts couldn't go in, and they had to find and use a stud for just ONE of the bolt locations. The weld on this one got real close (too close) to the hole as well. Check you headers before you install, a small jewlers file or a dremmel could have taken care of the weld, but not the pipe. Guess there are differences for all the savings!

3) While the Cooper rear valence does bolt right up, I need to get some of the wheel arches as well. The cooper is shorter than the S valence, so it looks a bit dorky now.

4) Like I mentioned above, it's hellasheously loud! I'll get a ressonator for it shortly. But a motorcyclist next to me on the way home said it sounded sweet. And he wasn't riding a harly!

After getting the header over the front sway bar....


The EGT


Alberto mounting the cat.


The Cat, and the EGT, Wide-Band O2, and post CAT O2


Choosing the muffler. We put them all onto the pipe and listened. They all sounded about the same, when not under load. So I went with the Magnaflow. A bit shorter, to give the guys some more room to work. The Bullits (Borla knock off from LA area) sound really good. The ricer one had a nice tone, but way too long!


Here's a shot from the back....


Matt

 

No resonator?

 

He didn't have the right one in stock (ID and length) so we skipped it for now. Also, the mufflers sounded good without it during the test, but that wasn't under load.......

I'll be going back to install one....

Matt

ps, I did a G-Tech run this morning, showing about 20 HP peak gains over the stock header and one-ball. And that was at about the same ambient as the day before....

 

One word: "Earplugs"

I know that my set up is great, because today I test drove a MCS JCW '05 and it did not measure to what I have in the old MCS '02. Do not get me wrong, I liked it a lot over stock, but I am happy with what I have. The OBX header is a good portion of what it makes it great.

Bomboasy

 

OK, so I've got some oscillations! I can feel it in the car when it rip, don't honestly know it's source yet, but now you know why I want some data logging!

So it shows a solid gain all over, despite the oscillations. I've looked at a lot of my runs, and many before the exhaust swap had the dip near the top. While the wide band is mounted, it isn't yet connected (running the wires this weekend), so I don't have A/F data yet....

Also, this shows a pretty modded car going up to 170 WHP. Not good. But it's the location, not the car. On the way to work this moringing, I did a measurment pulling away from a light, and got over 250 WHP! So location makes a lot of difference. Anyway, the place near my house gives the crappy numbers, and that's the one I had the pre- and post-upgrade data from. No, I don't have enough runs to know statistical valididty, but since all the data logging isn't hooked up yet, there's no point.

Anyway, they are what they are. They're best interpreted in terms of % improvement, but the oscillations up top make the comparison difficult.

BTW, the 0-60 times are meaningless. For an HP run with the G-Tech, you shift way early in first, so you can span the most RPM range in 2nd. The "250" HP run had a 0-60 of 5.707 sec..... And it had the oscillations....



Matt

 

No need to justify so much... Seems like you've got the right idea. Keep the variables as constant as possible & measure. Who gives a rats @$$ what number the dyno spits out? Dyno queens are just that Delta's are what matter.

I think you'll find that your fueling is going below 10:1. Further to this I bet the dip (and subsequent rise) are to do with open loop fueling followed by you maxing out your injectors' capabilities

Sight unseen I bet larger injectors & some dyno tuning will get rid of most 'O' that dip. ...The oscillations are another matter. WTF with that

EDIT: Wait a minute... you've got 380's installed, haven't you? Hmmmm maybe I'm talking out of my _ss.

Aside from all my babbling... hey thanks for such a great documentation of your exhaust mod. Looks ... nice & low-key Cooperish - very sleeper-esque. Be interested to hear your thoughts when you get the resonator on there... keep this mod report comming, it's a good one!

 

So my header just came in, and Im trying to decide on a place to get the weld done. The 2 guys I had in mind that could TIG the stainless to mild are both out (1 out of town, and one threw his back out), so that leaves me with welders I dont know, and dont have any referencs for. A welder friend who doesnt have the stuff to TIG suggested we just flare the cat by cutting the pipe up a little further to skip the welding, or get a mild-steel flare pipe to replace the stainless that OBX sent with the header.

Any suggestions on this?

 

It's not that big a deal... Have them tack the cat while mounted in the car, take it down, so they can weld all around neatly off the car. Any decent shop should be able to handle it...... If it's all welded on the car, they may run short of room on the top, and give you a crappy bead....


Matt

 

Dr. Obnxs, how is that CAT working out, are you getting any lights or setting any codes?

 

But I'm still working on sound. Still too loud!

Matt

ps, I've been putting it through the paces, and I haven't seen any codes, even hammering the motor when cold....

 

From the little I know about welding, welding stainless to mild steel isnt usually the easiest thing to do, and once done its pretty shady.

From a welding forum talking about welding stainless and mild steel exhaust parts: http://www.aws.org/cgi-bin/mwf/topic_show.pl?id=7432

"While it is entirely possible to weld stainless steel with plain jane mild steel filler metal the resulting weld (even if it looked good on completion) would be a metallurical mess and accelerate the corrosion of the stainless steel leading to a rapid failure of the joint."

When I called a local welding supply shop for references of good welders for a SS to Mild weld they refered me to 2 guys, both of which were swamped with work, and didn't know of anyone else who would do it.

From a conversation I just had with a welder: "Stainless steel, and mild steel have two different melting points, so you really need to use 309l filler metal that is high nickel/low carbon."

He also mentioned the need to TIG the weld rather than MIG it to assure you dont create a porous weld, and a couple techniques about gases when welding two different metals that I barely understood, so I wont get into it.

The more I look into it the more I think that your local exhaust shop will put a weld on your cat using a 308 filler metal which is the same stuff they use on mild/mild applications. Case and point: the two places I called up today, said they would just use their regular mild equipment to do the welding. This will result in a weld that will be highly porous and prone to corrosion.

So after my conversations, and research I think there are 3 options for a solid cat connection.

1. Find a welder who has the equipment, and knowhow to weld stainless to mild.

2. Find a mild steel flare to weld to the cat, replacing the stainless piece OBX sent.

3. Cut the cat off with enough pipe to get it flared so that no welding is needed. This is the first thing Im going to try, and I'll let everyone know how it turns out.

-Jake