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Thread: Custom QUIET Performance Exhaust

  1. #31
    Still Plays With Cars Loren's Avatar
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    Decisions made! Parts ordered!

    I'm going to go ahead and cut out the 1.5" restriction at the end of the header and run 1.75" all the way back.

    I got a high-flow 1.75" cat, 1.75" muffler and 1.75" resonator. The mandrel J bends that I got to put it all together are actually 1.875", and I bought a cheap pipe expander. I figure with extremely little expansion, I can make the pipes slip fit and maybe be easier to fit up.

    Did a little more research on cats. I'm sure I read all this before, but obviously, I needed the refresher. There are two kinds of cat substrate. There's the typical OE style ceramic material, and there's the newer metallic material. Both function the same as far as converting gases, but the metallic substrate is MUCH thinner, and thus offers considerably less restriction. So, the cat that I bought isn't actually labeled as a "high flow", but it is a Magnaflow spun cat with metal guts. And being 1.75" (when I only need 1.625" max), it should flow plenty for my needs. It was pricier than the 2" cat that I was looking at before, but the 2" was ceramic. What's another $40?

    Bottom line, I'm in for $219. That includes the $20 pipe expander and almost everything required. I'll need to find a flange gasket, some material for hangers, and schedule some time at Joe's Garage to put it all together.

    Parts should be here by late next week. I might have time to work on it sometime soon if I can coordinate with my buddy, Joe.

    ----------

    Expectations:

    All else being equal, if I just replaced the OE cat with a good high-flow cat, I'd probably gain about 1hp across the board, and maybe 2 at the top end.

    Getting rid of the 1.5" bottleneck throughout the entire system should free up another couple hp.

    Net should be pretty close to what SpeedCircuit's dyno shows with the header and no cat.

    I'd be pretty happy to just keep the gains that I already have and add a little more on the high end.

    And since I'm using a non-straight through main muffler, and a resonator that is a few inches longer than stock, I don't expect it will be much louder. Larger pipe will let more sound through, but I don't think it will be a lot.


    Simplify and add lightness.

  2. #32
    Senior Member Qrush's Avatar
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    I payed $300 for my Magnaflow setup. I thought it was a reasonable price w/installation. I pored over the numbers for days deciding on the pipe diameter and went with 1.75" as well. I feel it was a good choice given the power output. I was concerned about losing my "throttle braking" capability, as the Mirage does this well naturally, but I didnt lose that at all.

  3. #33
    Still Plays With Cars Loren's Avatar
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    I'll be over $300 by the time I pay for welding. I try not to think about it.

    If I've not mentioned it here, I've developed a philosophy over the years on the money I spend on cars. I figure I'm going to lose $2-3k per year on a car. I could buy a brand new car and lose that in depreciation, have a big car payment and no money to put into the car, I could buy a performance car and spend more money on tires, I could buy an older car and have a pretty decent modification budget... or in this case, I could buy a cheap economy car with a $150/mo payment and have a little bit of money to spend on it.

    But, any way you cut it, I'm going to spend $2-3k on a car every year. And I've made my peace with that. To me, a car is more than just transportation. It's a hobby.
    Simplify and add lightness.

  4. #34
    Senior Member Qrush's Avatar
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    Definitely. The money I saved both at the dealership and the pump, was put towards modifications. Ive spent plenty, but its the 1st car I have modified myself (mostly). So, its mostly a learning process for me. Im pretty green, but learning a lot and having fun while doing it. I use this car for work, so the mods help me to be more efficient on the road. My car is in a good place right now with the work that has been done so far. Not done yet, though...

  5. #35
    Still Plays With Cars Loren's Avatar
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    Parts are here! I may start doing some primary fitting (like verifying that there is space for the cat where I want to put it and making sure the flange hole is large enough to slide a pipe into) early in the week. And I have some time scheduled Wednesday afternoon with my welder friend.

    I think I should have enough pipe with what's included with the J-bends. If not, I may need to go buy a foot or so of additional straight pipe to fit it all together.

    1.75" pipe LOOKS really big when you're used to looking at 1.5" pipe.

    Simplify and add lightness.

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  7. #36
    Still Plays With Cars Loren's Avatar
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    Quote Originally Posted by Loren View Post
    Lastly, I've already seen my first Check Engine Light. It didn't come on immediately. In fact, it didn't come on until my second drive when I was cruising with VERY light throttle at 40-45 mph in 5th. I cleared it already, we'll see if it comes back. I think it was a P0420 code. Something about cat not warming up quickly enough or something. Basically, it's seeing the 2nd O2 sensor and with the cat missing, it thinks it's not warming up quickly enough due to the readings. If it keeps throwing that code, I'll try the spark plug anti-fouler trick.
    Installed a 90-degree O2 sensor adapter yesterday and reset the CEL. Did a fair bit of city driving last night, and it still hasn't come back on.

    You officially need one of these to run a header (or remove the first cat) on this car without setting a CEL:

    Simplify and add lightness.

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  9. #37
    Still Plays With Cars Loren's Avatar
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    Got the exhaust done today! Welds aren't the prettiest, but they are functional. We got everything to fit up pretty nicely. Only made two "mistakes". Cut one pipe too short by about 2" and had to scab a piece onto it. (one more seam) And then at the very end, we were too optimistic about the angle of the final tail pipe. Thought it was good. Welded it all together, fit it back onto the car... and it wasn't. We had to make a final angle adjustment.

    Neat stuff: I opted to not cut out the 1.5" pipe at the end of the header just yet. Partly just because I know I can do it later, and we had PLENTY of work to get done today just finishing the exhaust. So, there is a 1.5" restriction and perhaps "anti-reversion" feature at the header flange. Otherwise, we're 1.75 from collector to final resonator. The exhaust tip, just because Joe had a piece laying around from another project, is a piece of 3" stainless tube that we mashed in the press to make into a maybe 2.25" x 4 oval. Looks kinda neat. Also looks kinda ridiculously big. I thought it was kinda cute for a 1.2 liter engine.

    Spent most of the day on this. We started at noon, finished around 7, and spent another hour cleaning up. I did most of the cutting and fitting, but didn't touch the welder. And yet, because I was holding most of the parts as they were being welded, I have a wicked welder sunburn! Face and arms are as red as if I'd spent 4 hours standing in the sun. Wish I'd have thought to put on some sunscreen!

    Haven't had time to do any testing yet. Don't have the sound meter at home right now, but I can do acceleration testing... maybe tomorrow.

    Is it louder? Yeah. It's louder. It's not crazy loud. Idle sounds about the same, just a little deeper tone. Driving around with the windows up, even full-throttle acceleration to redline isn't even remotely "loud". But, it is louder than it was. And it may have a slight "drone" when cruising. Not sure yet. Mind you, I was driving home this evening with the radio off and specifically LISTENING to the exhaust. It's probably not bad enough that I'll notice under normal circumstances.

    I might not get my hands on the sound meter for about a week and a half, unfortunately.

    Oh, and the CEL hasn't come back on yet.

    Simplify and add lightness.

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  11. #38
    Still Plays With Cars Loren's Avatar
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    Passed the spouse test. Just went out to dinner, wife didn't notice anything different.
    Simplify and add lightness.

  12. #39
    Still Plays With Cars Loren's Avatar
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    Oh yeah, weight:

    As noted previously, the header weighs 4.4 pounds less than the manifold and cat that it replaces.

    The stock exhause from there back weighs 18.5 pounds. My replacement 1.75" exhaust weighs 20.5 pounds. So, 2 pounds more.

    Overall weight loss for the entire exhaust system = 2.4 pounds with the weight shifted slightly more rearward.
    Simplify and add lightness.

  13. #40
    Moderator inuvik's Avatar
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    Quote Originally Posted by Loren View Post
    Installed a 90-degree O2 sensor adapter yesterday and reset the CEL. Did a fair bit of city driving last night, and it still hasn't come back on.

    You officially need one of these to run a header (or remove the first cat) on this car without setting a CEL:

    Can you post a pic with the elbow installed to show how it fits in the space?


        __________________________________________

        click to view fuel log View my fuel log 2015 Mirage ES 1.2 automatic: 40.6 mpg (US) ... 17.3 km/L ... 5.8 L/100 km ... 48.8 mpg (Imp)


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