Another Dynomax VT thread - Pontiac G8 Forum: G8 Forums - G8Board.com
Exhaust Tech Headers, Catbacks, Mufflers, lack of mufflers

 
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post #1 of 15 (permalink) Old 03-16-2016, 07:03 AM Thread Starter
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Another Dynomax VT thread

Hey guys and gals. I recently bought a G8, and I want to change out the mufflers from Spintech to Dynomax VT's. The outside sound is incredible, but the drone is just too much for a daily driver. The forums seem to rave about the VT's, but online reviews are rating it typically 3.5/5. Most complain about flapper issues, but apparently it was an older design, and there's a different part number for one's with stronger flaps used in single muffler applications. I'd probably use this design to keep the car quiet when cruising and to avoid any flapper issues. My question is this, I have a procharged 6.0 that moves a decent amount of air, would I have any valve flutter issues at idle or cold start up like what some people with other vehicles described on places like summit and jegs? I don't see procharged G8 owners typically get these, so I can't really find any feedback from people with setups similar to mine. I'm probably just going to roll the dice and try it, but I just wanted to reach out here and see if there's anyone who's done it with FI or a healthy engine.

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post #2 of 15 (permalink) Old 03-16-2016, 01:27 PM
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I am cammed and have flutter issue at idle. Make sure you get the one with the stronger valve, I didn't, regret it now. Have had them on for 5 months now, sound great and keep drone away. I have the three inch in, three inch out since I have full 3 inch exhaust.

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post #3 of 15 (permalink) Old 03-16-2016, 01:52 PM Thread Starter
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Thank you for posting. It looks like I'll be going ahead and ordering the ones with the upgraded valve for sure.

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post #4 of 15 (permalink) Old 03-16-2016, 02:28 PM
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How can you tell which ones have the upgraded valve?

Also, I wonder if they all have the same valve and spring? For instance, does a 2.5" in/out have the same valve and spring as a 3.0" in/out? The size of your exhaust is going to effect the velocity of the air going through the muffler and could impact whether or not you get flutter. Whether they adjust for this in sizing the valve I am not sure.

I also read it's more of a problem with choppy cammed cars and cars without x pipes or h pipes.

2009 G8 GT - RotoFab, cam, Kooks mids, GXP mid, GT axle-backs
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post #5 of 15 (permalink) Old 03-16-2016, 02:35 PM Thread Starter
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The part number will let you know if it has the different spring or not. Doing a quick search on here will give you all the information you need on that.

The springs are not the same, on ones designed for single muffler setups have a stiffer version. I'll most likely be going with a duel 3.0" setup to support my plans down the road with a better H/C/I setup with the D series procharger, then eventually an F series.

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post #6 of 15 (permalink) Old 03-16-2016, 02:56 PM
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Wow. I did research them on here and that's all news to me. Glad I asked!

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post #7 of 15 (permalink) Old 03-16-2016, 04:42 PM
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No rattle here!

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post #8 of 15 (permalink) Old 03-16-2016, 05:24 PM
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works for me.

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post #9 of 15 (permalink) Old 03-16-2016, 07:12 PM Thread Starter
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I went ahead and ordered the 17597 3 inch mufflers. These are the ones with the stiffer spring, and right now Advance Auto Parts is having a great deal on Dynomax mufflers. $169.08 out the door with a $5 coupon I had. Once I get them, I'm going to take the spintechs off and put these in, I'll try to get before and after vids too. Thanks guys
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post #10 of 15 (permalink) Old 03-16-2016, 09:30 PM
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post #11 of 15 (permalink) Old 03-17-2016, 06:34 AM Thread Starter
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That's almost the exact same cam I have. Sounds great, but it doesn't sound much quieter than mine. Hopefully it'll be quieter in person, or at least drone a lot less.

2008 G8 GT - Not stock at all
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post #12 of 15 (permalink) Old 03-17-2016, 08:42 AM
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the drone is gone, not sure how car sounds from outside accelerating, my wife is the only other person who drives the car but she hasnt driven it since muffler and cam install. I may get her to drive it as I record her down my country road.

As for me and my house, we shall serve the Lord!!
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post #13 of 15 (permalink) Old 03-17-2016, 09:10 AM Thread Starter
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Good to hear, no pun intended. It'd be nice to cut down on outside noise since I live in an apt. complex, but drone is what I was primarily looking to eliminate or close to it.

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post #14 of 15 (permalink) Old 04-28-2017, 09:20 AM
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Did you ever install these? I have a pair new in box, but I want to make sure yours don't rattle first before trying them out.
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post #15 of 15 (permalink) Old 05-09-2017, 11:39 AM Thread Starter
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I ended up returning them. The engine blew soon after I bought the car, and I returned the mufflers due to offset costs on swapping the engine.

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