new exhaust = less power?

[6.0 Bio]

I've been looking at the 4" MBRP t-back (6212AL) to install along with the EGR delete I recently purchased, but I keep seeing comments in various threads about how after-market exhausts can actually cause a loss of power, most recently in the looney thread.
questions:

If I'm not towing heavy or racing and have no problems with EGTs (with my current use and driving style), do I really want to change exhaust and potentially lose power?

Does this power loss occur on aftermarket exhausts that eliminate the cat but still use a muffler (backpressure)?

Does it really make a difference on these kits that retain the stock-size down-pipe?

Sorry for the long post and multiple questions, but it seems like pretty much everyone agrees that exhaust is one of the best (and cheapest) upgrades you can make. I guess I just need convincing that the lower EGTs and slightly quicker spool are worth it on a truck that is otherwise all stock except for the tune.

Thanks

[Country Mav]

I put a 5inch on my truck. IF there was a loss of power, I couldn't feel it. Maybe if you dynod before and after you could see one, but I never felt it. I love the exhaust and I'm glad I did it.

[cowens677]

There is many magazine articles and website that show dyno #'s go up after a turbo back exhaust is installed plus lower egt's. I installed mine just a few days ago and it runs great, but I can not feel a gain or loss of power. I got it mainly because I wanted lower egt's and better mpg.

[the06wildebeast]

I'd imagine the "loss" of power is with the bigger DP the turbo may lag a little more. Exhaust is more of a lowering EGT mod than a power mod.

[sinner6.0L]

the benefits greatly outweigh any percieved loss of power

[cowens677]

But everything I have ever read never dynoed a loss. Has anyone dynoed a loss of power post an exhaust install?

[ralderman]

I think the turbo spools up faster, and definitely easier to hear. I didn't feel a power loss, I think it's worth it for the cooling alone.

[6.0 Bio]

Originally Posted by cowens677

But everything I have ever read never dynoed a loss. Has anyone dynoed a loss of power post an exhaust install?

Don't know. Never really considered it until seeing comments on here, and never really took it seriously until post #126 of the "well, I'm looney" thread. I believe Vivian knows what she's talking about when it comes to making power in these trucks (I run her looney tune myself), so when she said
"If you go with a 4 or 5 inch exhaust it will be louder but you will notice a loss of power. Happens to everyone. Do not be concerned."
that got my attention. So I figured I'd ask.

Call it playing devil's advocate if you want

I still think that increasing efficiency of air coming in and air going out is always a good thing since the engine is basically a big air pump anyway.

[cowens677]

I did not read that post, and you are right you would think she would know what she is talking about. But I would wonder why that is? And I would love to see some dyno result per and post an exhaust install.

[roadrunner]

My first 6.0, an '04, the first thing I did was cut the exaust off and install 4", aftermarket intake, and several other things I THOUGHT I needed to do. After all I was coming from a 7.3, it was well established those things needed to be done, right?

Fast forward to when I traded in the '04 to the current '07, me along with the rest of the world were much more informed with the workings of the 6.0. I think back and say why in the world did I cut off a stainless exaust system and replace it with aluminized pipe. Unless you're tuned hard and towing heavy the factory system is just fine. I have replaced the stock muffler with a Grand Rock straight through, and I think my kitty may have been poisoned or something, its guts exploded.

On the '04 going to 4" exaust I did notice more turbo lag, but no noticeable power differences. That truck was an "early '04", which means when the exaust is opened up the turbo effects on the ear were quite pleasant. I had a guy that worked for me at that time who lived on a busy two lane highway, when I would drop him off after work he almost would insist that I wait for a tractor trailer to be close before I pull out, that way they could hear me step on it, true story.