Flowmaster System with Cylinder Deactivation?

[daved931]

I recently got rid of my OBS Tahoe and picked up a low mileage 2008 Z71 with a 5.3. It has displacement on demand (cylinder deactivation).

I was looking at a stainless Flowmaster American Thunder system with a 50 series muffler. How will this sound on the highway when it drops down to 4 cylinders? I don't want to sound like a ricer. Ha ha ha.

I'm open to other suggestions if people have them, though I prob cannot afford something like a Corsa right now.

[joe_too_crazy22]

You won't even notice. A buddy has the '10 with a 40 series and can't tell. I also have a coworker who has an '09 with the 6.0, but I'm not sure that motor has the vvt, because he's always complaining about his gas milage.

Also, unless your coasting or on a smooth highway, the cyl deactivation will hardly take over. There has to be a certain amount of load taken off the trans to signal the vvt to open. Unless you plan to drive only 55 mph on the freeways, is mostly a gimmic. Just my .02

[Koots]

I heard it tends to sound hollow and strange, but if you plan on throwing a larger set of tires on or something, it's probably not gonna hit 4cyl mode very often.

My parents 09 Sierra rarely did, but i could barely keep my foot out of it. Trying to drive in 4cyl. mode on the highway is definitely stressful, as you will probably be holding up traffic. I tried everything to get it to achieve awesome mileage, but after nearly 15,000kms put on it, i managed to make the AVG. MPG on the DIC display to jump from 15 to 16.5MPG.

Not too bad considering the power it has available at any moment. My K5 gets 16MPG but you won't see me going any faster than 65MPH :lol:

[daved931]

Thanks for the info, guys. The more I drive the truck, the more I've noticed the mileage isn't a lot better than my old Tahoe on 33's with a 350. Kind of surprising (disappointing maybe?). Oh well.

Anyway, it doesn't seem to be dropping down to 4 cylinders at all, really. I guess I don't have much to worry about.

[Andrew.]

When it kicks in, it'll sound like a chopper. *SOI SOI SOI*

Get a tune and deactivate it.

[Badass69]

When it kicks in, it'll sound like a chopper. *SOI SOI SOI*

Get a tune and deactivate it.

And while you are at it go nuts and get a non AFM valley cover and ditch the junk failure prone AFM lifters. Then you have a pretty decent 5.3 that has the 243/799 heads and 87 mm Trail Blazer SS style intake manifold.

[daved931]

I passed on the Flowmaster and ordered a Borla system today. A little more scratch, but should be worth it.

[Andrew.]

And while you are at it go nuts and get a non AFM valley cover and ditch the junk failure prone AFM lifters. Then you have a pretty decent 5.3 that has the 243/799 heads and 87 mm Trail Blazer SS style intake manifold.

http://s18.postimage.org/nhjvsub15/1312094366871.jpg