I thought you couldn't run off road x pipe. You can't run regular catted x pipe either? Or are you saying you can't mess with the stock cats?

 

You can easily run a catted X. I ran offroad for a while, but went back to catted because it was too loud. You don't even have to smog for like 5 years right? IIRC, you're law enforcement, so you'd get off even easier with a catted mid pipe!

 

Did you adjust your tune in between the swap? Do you have a tune on it? I would imagine that you would need to re-tune for the significant change in airflow, otherwise your car would run too lean and your ECU would dial back your timing.

It just seems like you disproved your own theory here. You thought that the Magnaflow Competition axle backs made you lose power because there was no backpressure, so you went to the factory exhaust (lots of backpressure) and nothing changed. Then you went to the Magnaflow Street axle backs and your car was running right? It just doesn't make sense if backpressure is the culprit. I'm guessing that either you needed a tune, or you didn't give time for the ECU to learn the new setup on either of the first two exhaust swaps.

 

Cant mess with stock cats. So any "catted" pipe is out.

Yes I could swap out when I go for smog but right now I have no where to store anything (studio with no garage) so that idea is out. If I had a out of view place to store the stock I would jump all over it.And yes I am haha so I am sure I could but that would be illegal and I would never want to use my position to get around the law.

Matthew

 

Lol I hear ya. I just know that people get away with WAY worse in LA County!

 

You don't need a tune or a change to a tune for axle backs.

I said i lost power (low end torque) with the Competitions because not enough backpressure. I lost power (low end torque) with the factory axlebacks because too much back pressure.

I let a friend use my Competitions for a month or so. At the time all he had was a cut and clamp x pipe. He told me he noticed a loss of low end torque.

 

http://www.mustangevolution.com/forum/f312/t296628/
Backpressure is not the culprit here.

I agree that you don't NEED a tune for axle backs in the sense that you can run the car without it, and for most axle backs there isn't enough of a change to warrant one. But judging by the significant changes in performance that you're talking about, I would say that it's changing your A/F ratio enough that you should have a tune to get any kind of result out of the change. Also, you're not really changing axle backs here, you're basically going from axle backs to straight pipes with the Competition system.

The A/F ratio is all that it really could change. You have the same diameter piping, your exhaust gasses are flowing at a much higher velocity because of less restriction. It flows the air out so much faster that your engine can pump in air faster, so your engine starts running lean due to too much air and no tune for more fuel, so the ECU compensates by retarding timing so you don't blow your engine by running too lean.

If it's really as big of a difference as you claim it is (and I believe you that it is), I think that throwing a tune on for the change in air volume flowing through would be a good idea. You're talking about going from a system with giant mufflers to basically straight pipes, it's a big difference.

Sounds like you already swapped back and are happy, but it would just be interesting to see if a tune would change things there.

 

So, you don't NEED a tune for the axle backs. Do you NEED a tune for the shorty headers?

 

A tune is not required for the headers or mufflers. You will see minimal gains. I did a data log with both and Bama revised my tune.
My mufflers made a very noticeable gain. It was also the last part added to my exhaust system.

 

I agree, mine too. Axle backs don't get enough credit, solid gains to be had.

 

After months of sitting in the garage I finally got my BBK shorty headers installed. Two things! One I def. feel that I got my low end power back after I lost some and gained mid/upper power from the intake manifolds and two always check your parts throughly as I didn't see some weld splatter on one of the tubes and it is in the field of view and its been so long now that I can't return them!! Oh well lesson learned, check your ****!! lol I got them for cheap so I'm not too mad $280 new (ceramic). Heres a few bad cell phone photos of the stock headers and BBK. Oh and I love how it made the exhaust note deeper on my already deep sounding Mag street cat-back. Didn't make it much louder which I kinda want . Borla S-types?

 

Does anyone know why my stang might be idling rough? Whenever the engine/rpms are at idle whether I'm driving then at a stop or just sitting with the engine running the engine has a weird vibration.

 

Looks good Anthony. Could be your idle is relearning. Also make sure everything (bolts) is nice and snug. Make sure you didn't push on your cai during the install of your headers. One of my clamps came loose and my cai tube slid out just a little letting too much unmetered air go into the engine making it idle rough.

 

Thanks David, everything should be tight as I did do a heat cycle. I'll check over everything again.

 

I had idle issues with the Bama tune that the MPT solved. Not sure who you're using.

 

No I'm still with Bama at the request of my Wife. She never says anything when I buy mods but she wasn't ok with me leaving the tunes for life with Bama without seeing if they can get it right lol. I gave in and said ok. I just decided to send them a bunch of dataloggs with various conditions and we worked out our issues between each other. Anyway that was before the headers so now I'm going to be working with the same tuner to see if we can get it worked out again. I'm still gonna get either a Steeda or MPT tune.

 

Give them another shot. I had problems too, but recently tried again and things seem to be all good now in my case. Theres been updates. Idk if itll fix your issues but im just saying it worked with me

 

You also need to make sure you get the idle relearn process done.

 

Really enjoyed my bbk headers last season as well! Cant wait till spring again!

 

I just ordered a pair of Pypes high flow cats and will update soon with a new vid. They should change the tone for my setup.