Installation of a Flowmaster Force II Cat-Back Exhaust (#817523) on a 2011 GMC Sierra. I made this video because I was researching installing one of these on…
Flowmaster Cat-Back Exhaust Install on 2011 GMC Sierra
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From Flowmaster FAQ: “There are some modifications that have the potential
to void a vehicle’s factory warranty, but modifying the exhaust system
after the catalytic converter is not one of them. All Flowmaster exhaust
systems are designed vehicle specific and do not violate manufacturers
factory warranty. If you’re having problems regarding this issue, please
contact sema.org for more information regarding consumer’s rights on
performance aftermarket parts.”
hey man truck sounds great. i was just wondering if this voids any warranty
on the truck?
thanks for the help! my manual says i need to loosen the ball clamp right
behind the cat (the one i broke the bolt head off) so i can rotate the pipe
for fitting, but its a round pipe, i hope i can slide the adapter right in
like you did. and mines a 2010, not sure if there is much difference
between 10 and 11
yeah, I left the flex pipe on. My instructions didn’t tell me to take it
off. All the measurements for the exhaust were after the flex pipe. To
answer your question, I had plenty of room. Before I cut/clamped or did
anything, I measured several times w/ the exhaust laid out and assembled
off to the side of the truck to give me the confidence that it would fit
before I did anything permanent. You can try that to see how it would work
out for you. Hope you don’t have to make any cuts. Good Luck!
hey man, did you have to loosen the ball clamp that is like 3 inches off
the cat? instructions said too, and the head snapped off the bolt. it looks
like you left the flex pipe on and there was enough room to install. Thanks
in advance!
Good job buddy!
why would you start a vehicle in a confined space like that
You can drop the hangers and remove them out of the truck. So much easier.
It happens more than you would think really. On the highway in cruise
control it will kick into V4 and stay there for a few miles or until I hit
a hill of any kind. I don’t have any real data but empirically I feel as
though I hit V4 mode more often with the new exhaust than I did with the
stock. I would attribute this to the addition of the exhaust and the cold
air intake making the engine more efficient.
I cut my original exhaust behind the muffler for easier removal, nobody
wants that stock crap anyhow … IF someone did buy it they could have it
welded. You don’t need a torch to bend the hanger, but I agree taking it
back out is much easier to bend it. All you need is a deep socket and some
extensions for leverage and it will bend with a little muscle. I always go
back and re-tighten all the clamps after the system goes through a couple
hot/cold cycles to make sure it’s good and tight.
Good informative video Bro. I’m thinking of getting this for my truck but
with duel exhaust. What kind of cold air intake filter are you using if any?
Great video!! just a tip for ya if you don’t plan on keeping the stock
exhaust you could have cut it one more time to make it easy to remove
around the back axle! helps with the hangers too!! cheers bud!!
That sounds just ok..
nope. They only time I really get any drone is when my truck goes into 4
cylinder mode (my truck has the active fuel management and will switch from
V8 to V4 when it notices less load to try and save gas. It can be a little
irritating).
yeah, I was trying to keep the stock exhaust intact as much as possible in
the hopes that I might be able to sell it or something. That’s not working
out so in hind sight, I should have just cut it again. Good point though.
To get the tailpipe clearance all you had to do is use someones torch or
buy a small one from walmart etc and just heat the back hangar enough to
adjust the clearance on the tailpipe
did the ”check engine” signal showed up after installing the exhaust?
if you put wd40 or any other lubercant the hangers will slide out of the
rubber housing
I heard it rarely happens though, is it THAT much of a problem?
ah I see what you mean. By the way, have you thought about getting a
performance tune? I myself installed a Magnaflow cat-back on my Tahoe, and
threw in a K&N FIPK as well. Could definitely feel the better throttle
response, but have been given advice on how to get the best out of these
two upgrades, and that’s with a tune. I was recommended Black Bear
Performance but there’s others that might get you the desired results.
nice job……well done……sounds nice too.cheers
Very nice
Honestly sounds the same? Take the cats of get a tune that’s what I did and
it made that exhaust come alive headed to in Maidenhead that stupid fuel
saver shut off also now my truck runs and drives like a truck
Sounds awesome thanks for sharing
very good tutorial
3 People drive Toyota echos and eat their corn the long way.
do u know what series muffler that is??
heads up, to get your hangers to fit nice, use a torch to heat them up til
they glow and you should be able to mold them down a bit lower.
I have the K&N cold air Intake.
I’m pretty certain it’s the “Super 50” series
@lifeasmommy that’s exactly what i did. my problem getting the stock
exhaust out was due to space under the truck. in hindsight i should have
just cut it again. it wanted to keep it whole to sell or something but it’s
still sitting on my garage floor. should have just cut it 🙂
You get much cab drone when driving?
Thanks a lot, definitely going to put this system on my truck!
@mrfa9lavip nope. i haven’t had my check engine light come on at all.