New exhaust mod

AZS10Crew · Post by **AZS10Crew** » Wed Aug 13, 2003 8:45 am

Well...I ordered my newest toys yesterday. An exhaust cutout and a McCord Power Plate. For any of you that don't know, the exhaust cutout is spliced into the I-pipe before the muffler to allow for open exhaust. The McCord Power Plate allows me to open and close the cutout from inside the cab with the flip of a switch. I had one on my Z28 and loved it. It was always fun to flip open the exhaust next to a ricer and rev at him.

Just out of curiosity...how big is the exhaust pipe just before the muffler? 2.5" or 3"? I ordered the 2.5" cutout, so there might be a bottleneck just before the muffler. Oh well.

a2b · Post by **a2b** » Wed Aug 13, 2003 10:17 am

Dragonmaster · Post by **Dragonmaster** » Wed Aug 13, 2003 10:39 am

2.25" so you should be ok

Warnoffroad · Post by **Warnoffroad** » Wed Aug 13, 2003 12:51 pm

Arent those like 500? I saw them on trucks but didnt remember what the web page was. I was wondering how that little servo would stand up to mud. Lets us know how it sounds and holds up.

AZS10Crew · Post by **AZS10Crew** » Wed Aug 13, 2003 1:34 pm

warnoffroad wrote:Arent those like 500? I saw them on trucks but didnt remember what the web page was. I was wondering how that little servo would stand up to mud. Lets us know how it sounds and holds up.

It held up great on my Z28. It was never submerged, but it got wet in the rain a few times and still worked OK. It was only $110 too. You can order them here. They can be stand-alone units that attach to the end of a cutout or you can order ones that insert into a Borla system to take the place of the various plates.

Mike H. · Post by **Mike H.** » Wed Aug 13, 2003 3:21 pm

Are you installing that upstream or downstream of the cat? When I did my Gibson, I ran my truck without the muffler and entry pipe to hear the sound. It was not very loud or impressive at all. I was very surprised.

Upstream of the cat I'm sure it would be.

AZS10Crew · Post by **AZS10Crew** » Wed Aug 13, 2003 3:39 pm

It will be after the cat but before the muffler. I don't think there's a place to put it before the cat. And even if I did, it would probably throw a code because the O2 sensors would get bad readings.

I'm not really looking for it to be terribly loud, just better flow and sound than the stock muffler. And the power plate will allow me to make it quiet when I have people in the truck or if I just don't want to hear the noise.

Mike H. · Post by **Mike H.** » Fri Aug 22, 2003 4:53 pm

Did you get it and put it on yet?!? Don't tease us - fill us in!

AZS10Crew · Post by **AZS10Crew** » Fri Aug 22, 2003 9:26 pm

Mike H. wrote:Did you get it and put it on yet?!? Don't tease us - fill us in!

Sorry...not yet. I got the cutout right away from Summit, but the Power Plate won't be here until late next week. The place that makes them manufactures each one to order and tests it before it's shipped, so it takes a couple weeks from order placement until receipt. i should hopefully have it on by the end of Labor Day weekend.

WFRager · Post by **WFRager** » Wed Aug 27, 2003 2:37 pm

Mark-

I too sold my Z28 ('99 HO SS) for my crew. I had headers, no cats and an SLP Loudmouth (among other mods). That thing was so obnoxiously loud! I guess I'm getting too old for that kind of noise.

I do miss the power though!

Mike H. · Post by **Mike H.** » Fri Aug 29, 2003 3:49 pm

AZS10Crew wrote:It will be after the cat but before the muffler. I don't think there's a place to put it before the cat. And even if I did, it would probably throw a code because the O2 sensors would get bad readings.

I'm not really looking for it to be terribly loud, just better flow and sound than the stock muffler. And the power plate will allow me to make it quiet when I have people in the truck or if I just don't want to hear the noise.

Mark, I'm curious. Are you going to try it (temporarily) with the muffler removed before you go do all that? When I did the Gibson, before I put it on I started the truck in my garage, let it idle some, reved it some and held it mid range some. I was shocked at how QUIET it was. The pre-cat and main cat do an excellent job at killing the sound (which also means they are killing free flow ). I almost left the Gibson off, but there would have been a major restocking fee to return it (the shop special ordered it). I (regretfully) went ahead and installed the Gibson.

You may find yourself leaving the plate open all the time. Depending on how you report the sound level is on the road, I may remove the Gibson and the tail pipe, and run a NASCAR-type open side outlet out the passenger side in front of the rear tire. Maybe with a wide/flat polished stainless tip.

I'm glad you are not getting it for it "to be terribly loud". It won't be. The open cat is not loud. Please let us know the difference.

AZS10Crew · Post by **AZS10Crew** » Fri Aug 29, 2003 3:59 pm

I haven't tried it with the muffler unbolted. I figure any bypass of the muffler is more free-flowing (and louder) than stock. I'm not really looking for anything super loud, because I know it's only a V6, and there's a cat and pre-cat to quiet things down.

Also...I like the choices that the electric cutout plate gives me. Even if it's not terribly loud, it's still louder than stock, cheaper than a cat-back at only $140, and flows just as well. And for my job, I have to go visit clients all the time, and it's much more convenient to just flip the switch and quiet down the exhaust rather than having it be louder all the time. Also when driving with friends to dinner or something, a quiet exhaust is better. My mud-terrain tires are loud enough as it is, no need for extra noise all the time.

Mike H. · Post by **Mike H.** » Fri Aug 29, 2003 4:10 pm

It will definitely be somewhat louder than stock, no question. But I think you'll be surprised. It will be nothing like open exhaust without any cats. That is extremely loud.

Comparing what I heard out of the open cat before I bolted on the Gibson, I regret putting on the Gibson.

I know what you are saying about the BFG M/Ts. They sing a tune at highway speed. Kind of hypnotic, puts you in a trance at night.

Let us know how it goes. Do you have any capability to do a couple of sound clips (open vs. closed)?

AZS10Crew · Post by **AZS10Crew** » Fri Aug 29, 2003 8:30 pm

Unfortunately sound clips aren't an option.

But I'll try and get pics and stuff.

QnsRyche · Post by **QnsRyche** » Fri Aug 29, 2003 8:32 pm

its 3"

AZS10Crew · Post by **AZS10Crew** » Sat Sep 06, 2003 1:37 pm

Well...got everything installed on Thursday. Sound is about what I expected...not terribly obnoxious, but noticeably louder than stock. It resonates a lot in the cab with a nice deep tone under moderate acceleration, but it's not too annoying. Not sure about outside sound, but I assume it's OK. The electric cutout plate works great as well. Just the push of a button and it opens and closes when I want. The LED and switch look good on the panel next to the radio also. And thanks to brule for the wiring explanation...works perfectly.

Pics will be up eventually...once I get my new wheels I'll have a "catch up on mod photos" day.

a2b · Post by **a2b** » Sat Sep 06, 2003 9:58 pm

sweet.

mabey you can have your truck in your avatar face the other way since everyone likes it facing to the left

Mike H. · Post by **Mike H.** » Sun Sep 07, 2003 3:51 pm

Does it dump directly under the cab, or did you pipe it out the side out from under the truck? Did you notice any performance gains or decreases? And no check engine light activations?

AZS10Crew · Post by **AZS10Crew** » Sun Sep 07, 2003 4:40 pm

Mike H. wrote:Does it dump directly under the cab, or did you pipe it out the side out from under the truck? Did you notice any performance gains or decreases? And no check engine light activations?

It's pointing basically straight back under the back part of the cab. It's welded into the I-pipe between the flange and the muffler. Since that section is at an upward angle towards the rear, and the cutout is mounted to angle down from the main pipe section, it winds up pointing basically straight back. I have a small section of pipe with a flange that I could have used to direct the flow further away, but with the body lift, there is plenty of clearance for the new exhaust exit. And the short pipe would have caused some serious ground clearance issues.

No performance gains that I can tell. Even on my Z28, the cutout only gave me about 15-20 HP. But...that was a percentage gain...not a gain that can be seen on all vehicles. I figure it may have gained 10HP at the most...which isn't really noticeable by the SOTP.

No SES light...and I doubt I'll ever see one caused by the cutout. The O2 sensors are still getting readings just as they always did. None of the emissions equipment is bypassed...only the muffler and tailpipe.

Mike H. · Post by **Mike H.** » Sun Sep 07, 2003 5:10 pm

Do you think it would be objectionable (sound-wise) to remove the muffler and tail pipe back to the stock flange ahead of the muffler, and then route a pipe from the flange out the passenger side just in front of the rear wheel? That would get the sound out from under the truck and direct it away from the cab. I'm really wanting to try that.

AZS10Crew · Post by **AZS10Crew** » Mon Sep 08, 2003 6:54 am

I think that would be OK. Remember though...you're not going to get a V8 sound out of your truck. If you have visions of it sounding like a V8, then you'll be disappointed. It sounds louder and pretty deep at lower RPM's, but when you're on the throttle, it doesn't have the same rumble. It sounds like a V6 with no muffler. That sound is OK for me, but it might not be for you. It doesn't sound like a rice rocket, but it won't sound like a 350 small bock either.

You might try just unbolting the muffler first and driving with it open to see what you think. I knew what a V6 with open exhaust sounded like because my first V6 Camaro had open exhaust, so I knew what to expect.