Finally swapped the stock exhaust for a Magnaflow cat-back exhaust (part# 16630) on my 2008 3.7L with 116,000 miles. Really happy with the results and the deep tone from the exhaust. I spent a lot of time going through old posts in this forum and others before pulling the trigger and what I found was that most of the discussions on the sound and any drone revolved around the Alphas. I made a video that hopefully provides some insight on what you can expect when installing on a 3.7L. General consensus seems to be that there is a noticeable difference in sound between the two Tried my best to capture the sound from the stock system and then after the Magnaflow was installed but I'm pretty limited with just an iPhone for the recording.. I wrote a bit more regarding my specific thoughts in the YouTube description if you're interested but in general, I am really happy with the outcome. The low growl from the exhaust is great and I haven't felt that the "drone" is unbearable as some people have stated. I like hearing the low drone actually. It's definitely a mod – albeit and expensive mod – that I would recommend to others if asked. Here's the YouTube video:

 

That is nice. Why the sputter on RPM drop with the new exhaust?

 

Wish I had an answer for ya. You might be interested in my post from a few days ago Rough Start with Random Stalling. I've had an issue with rough starts and cylinder misfires since 2014 maybe that I've never been able to figure out. Listed everything I have done that might remedy the issue but nothing has worked. I've speculated for a year or so that I have soft valve seats and that's the root cause but I'm just not sure and have learned to live with it. Maybe someone with much more knowledge than me on the inner workings of an engine and combustion will share their thoughts on that.

But yeah, I love the Magnaflow. Really happy with the look, sound, everything so far.

 

Any Gains? HP, fuel etc.. I was just looking into this system and a borla. Trying to compare

 

I think a lot of that depends on any other mods you have on your H3, driving style, if you live in Breckenridge, CO. any issues that could impact fuel economy or performance, etc. The general consensus seems to be that adding a cat-back exhaust does improve things like overall HP but unless a dyno test is performed on my car before the mod and then after, I would be wary in claiming "I got an XX HP gain by installing a certain exhaust."

For me personally, it's hard to say that I've noticed a significant improvement in power since installing the Magnaflow. I do have a PCM tune and Air Doc intake on my H3, but I also have one bad catalytic converter as well as a consistent P0300. Does this impact performance at all? Maybe. I did fill the tank all the way up and set my trip odometer at 0.0 miles. Right now I have about 1/8 tank left and the odometer reads 234 miles, although I've been excited to hear the low growl of the exhaust which has probably caused a bit of a lead foot. I don't have an opinion on Borla vs. Magnaflow; however, if I could have purchased the GM Performance exhaust made by Borla then I would have.

 

I don't hear a difference between these two.
Just sounds the same. The best exhaust I've heard was awhile back on YouTube of a H3 with glass packs. I'll stick with OEM though because I like the stealth quiet ride ha!

 

Thank you. Very helpful

 

Never confuse LOUD with POWER, not even in Hummerville. Nothing less impressive than a Loud terd going nowhere when on the throttle.

Anyways, H3s are slow, loud H3s are just as slow. Upgrading to a quality CAT Back system by itself will get you some controlled sound, not going to do anything for "performance" all alone. Add ons: a Port Polished Throttle Body, Intake, PCM Tune and Efan conversion to that CAT Back system, then you will see performance. Any one of those add ons by itself will do significantly more than exhaust for performance.

 

Thank Doc,
I have the the Performance throttle body the CIA and now PCM, still trynna find out if these systems do anything worth the money for performance. Loud isn”t my quest. Maybe some dyno results might help here. Before i spend another grand or 2 on an exhaust for only 3hp gains or a lost of 6 mpg. (Not actual ending result numbers.)
But I will just dyno my h3 like Happy Hummer said with all the considerations per driver necessity. And go from there.
Thank All