axle back deleted mufflers? lost power it seems

[Vash]

Originally Posted by camarossrs2150

my car seemed very fast . with no sound . now that i cut my mufflers out .it seems slower . when i floor it it feels like it is holding back .does not seem as fast but does have sound . what else do i need . im thinking air intake system to get that boost back . please il take any suggestions thanks . what is tune mean and what is it for .reading alot of people getting it tuned for 200 to 400 bucks

How many miles, last oil change and are you running Royal Purple 5/30?

Also maybe it's a fuel and outside air temp issues. I don't think you would loose power unless there is something in there. Some longtubes are packed.

Are yours just straight pipes? You didn't just cut them off right?

[96rss/ls6]

Originally Posted by 1320junkie

DING DINg DING we have a winner..you can mod intake and exhaust without a tune...it takes the ecu sometime to recalibrate...you do not void your warranty this way..you start getting into tunes and you void your warranty.

Thanks guys, Ive had a lot of experience in building these lsx engines,they react wierd to different things. but ive never seen one be hurt from freeing up some breathing room. And when it comes to voiding your warranty with a tune, you can always have it re-mapped before taking it in to the dealer. This is a kind of costly move but is much better than voiding your warranty. For all the guys worried about back pressure, look at all the guys running cutouts and the power they gain, thats straight headers, no cats, no pipes, no mufflers. And for you L99 guys these cars are much more affected by the computer than LS3 engines. Your shift is controlled by air temp, timing,throttle,torque,weight,many variables. Dyno/Tune !!!

[camarossrs2150]

Originally Posted by Vash

How many miles, last oil change and are you running Royal Purple 5/30?

Also maybe it's a fuel and outside air temp issues. I don't think you would loose power unless there is something in there. Some longtubes are packed.

Are yours just straight pipes? You didn't just cut them off right?

850 miles running with royal purple been in the low 80s and we cut out mufflers put straight pipes in with existing tips .would be the same as slp loud mouth 1 muffler delete using 93 oct. one day i screwed up and put 10 dollars of 87 by mistake which is about 4 gallons . caught it on time i hope .feels like its pulling back .i have no cai yet .im thinking the little air im getting in with that paper filter might have something to do with it . im not a pro thats why im here asking . im just guessing can use all the help out there . thanks .

[96rss/ls6]

Originally Posted by camarossrs2150

850 miles running with royal purple been in the low 80s and we cut out mufflers put straight pipes in with existing tips .would be the same as slp loud mouth 1 muffler delete using 93 oct. one day i screwed up and put 10 dollars of 87 by mistake which is about 4 gallons . caught it on time i hope .feels like its pulling back .i have no cai yet .im thinking the little air im getting in with that paper filter might have something to do with it . im not a pro thats why im here asking . im just guessing can use all the help out there . thanks .

Paper filter has nothing to do with it unless it has a trash bag over it. 87 octane has nothing to do with it either. You might here a slight ping on hard acceleration with 87 if you didnt have the muffler delete but its doubtfull, either way it wouldnt hinder performance enough that you could tell. My dealer filled mine up with 87 on the day I brought it home. those arent your problems.I would be checking for loose sensor wiring in the engine compartment. Then start trouble shooting. Put the car on flat ground and see if you can push it in nuetral, see where the car is shifting when at wide open throttle, make sure the car is shifting thru all 6 gears( not taking off in 2nd) Keep looking for things of this nature that would make it slow. Another thing as I mentioned earlier, let it sit idleing for 15 or 20 mins to re-learn, if these things dont help , you can probably remove your battery cables and let the car sit about 30 mins, for the capacitors in the ecm to die then hook it back up and let it idle for a while, then drive it around easily to let it reboot. I could go all day!!! only thing I dont know with the new car is if you disconnect the batt cables if it will piss of onstar? anyone know?

[camarossrs2150]

Originally Posted by 96rss/ls6

Paper filter has nothing to do with it unless it has a trash bag over it. 87 octane has nothing to do with it either. You might here a slight ping on hard acceleration with 87 if you didnt have the muffler delete but its doubtfull, either way it wouldnt hinder performance enough that you could tell. My dealer filled mine up with 87 on the day I brought it home. those arent your problems.I would be checking for loose sensor wiring in the engine compartment. Then start trouble shooting. Put the car on flat ground and see if you can push it in nuetral, see where the car is shifting when at wide open throttle, make sure the car is shifting thru all 6 gears( not taking off in 2nd) Keep looking for things of this nature that would make it slow. Another thing as I mentioned earlier, let it sit idleing for 15 or 20 mins to re-learn, if these things dont help , you can probably remove your battery cables and let the car sit about 30 mins, for the capacitors in the ecm to die then hook it back up and let it idle for a while, then drive it around easily to let it reboot. I could go all day!!! only thing I dont know with the new car is if you disconnect the batt cables if it will piss of onstar? anyone know?

not sure but i think i read something about car taking off in second gear. anybody read something about that

[96rss/ls6]

You definately need to count your gears from takeoff. Or shift it to 1st manually and see if its any better.after that get someone to ride with you and stopwatch you from 0-60 and see whats going on. This will tell you if its you or the car. hope you figure it out. If you need help you can pm me. I will try to help.

[lawdogg149]

Right on guys. I have nothing to sell or prove to anyone. I ran my car on the dyno to just see what the difference was. 17 hp and 10 fttq is the results. Thats just the honest truth. We all have the LS3 motors that have done this mod as well. IMO you are hearing the sound but don't feel the go to go with it. Go to a track and record some times. No way you are losing anything with deletion of those 18 lb mufflers. Again the difference is in the sound and perception of movement.

[LDGn63]

Here is another thought. (though highly unlikely)
could it be possible that the muffler shop bender (not mandrel) could have crimped the pipes enough to actually be MORE restrictive than the muffler? I had 2 bends per pipes instead of one big bend.
I can't imagine thiswould be the case but what do I know! LOL

[D1BADZ]

Originally Posted by lawdogg149

Right on guys. I have nothing to sell or prove to anyone. I ran my car on the dyno to just see what the difference was. 17 hp and 10 fttq is the results. Thats just the honest truth. We all have the LS3 motors that have done this mod as well. IMO you are hearing the sound but don't feel the go to go with it. Go to a track and record some times. No way you are losing anything with deletion of those 18 lb mufflers. Again the difference is in the sound and perception of movement.

i agree its a sound and movement perception. b4 muff deletes it pulled hard and was quiet. now it pulls just as hard and is loud.

with muffs on you can hit 4k rpm and not be that loud

with muff deletes around 2.5 3k it sounds like your really getting on it and hitting high revs.

[Icntdrv55]

So, has anyone done a muffler delete on an L99? If so, how does it sound, especially on the highway when the AFM kicks in? Do you get a lot of Popping, especially on Deceleration?

I heard a LS3 with Muffler delete this past weekend and it sounded GREAT, not too much popping or anything.

[camarossrs2150]

my l99 sounds great it just seems to have a slight miss .maybe it is the preception of noise to speed .i called slp today and they told there has been no complaints from the muffler delete .that maybe it is mind over matter .also they said that the computer dont have to catch up with the change .mufflers would not have anything to do with the computer .thats what they said .and i think he is right there .just not sure if its back pessure or me .some other guys are saying they have the same problem .maybe we are all crazy

[96rss/ls6]

mine has that little miss during idle. Everyones does that , it just wasnt nearly as noticeable before because you couldnt barely hear it. And thats good to here lawdogg. 17 hp is nothing to sneeze at for the cost of the delete. As far as the computer goes, My LS6 ran much more lean until I reset the computer. After reset it came back to almost stock. Then with tune and injectors 47 hp. Anyway if you think about it more airflow is escaping which lets more air pass the oxygen sensors, and also free's up room for more air to be brought in via the intake system. So your talking about several sensors. Thats why the muffler delete benefits sooo much from CAI install , everything flows much more free. But anyway thats just my opinion, and my experience with autotap/dyno's

[camarossrs2150]

went out this morning it was 64 degrees out .shut off tc and stability warmed up a little ,gunned it and took off like michael jackson . this bike thaught i was racing him . lets say at 145 his girl on the back wasnt digging it .it feels like im getting my power back from the muffler delete.my chick was not digging it either .

[Rodrunner]

"If you reduce the back pressure to much you will actually lose torque. You need back pressure."
You've got to be kidding.

"Loud is not a telltale sign of power. Now IMHO it's a telltale sign of ignorance."
Tell that to John Force, Jeg Coughlin and Tony Schumacher!

Too many people here are acting like they know what they're talking about just to impress someone. The Mods should be setting these folks straight!
Listen to 96rss/ls6, camarossrs2150, smart guy. Like 2010 SS RS said, he's seen gains although it may take your ECU time to learn the correct setup. Also, like Camaro5 said, some actual times would let you know if it's for real or just your imagination. And a tune....make your changes, tune the car, then come back in a month or so, redyno and see how much of that tune has been lost to your ECU.

Originally Posted by Icntdrv55

So, has anyone done a muffler delete on an L99? If so, how does it sound, especially on the highway when the AFM kicks in? Do you get a lot of Popping, especially on Deceleration?
I heard a LS3 with Muffler delete this past weekend and it sounded GREAT, not too much popping or anything.

Did it Friday. Awesome sound. Not too loud at idle (shouldn't be at 500 RPMs), yet very powerful sounding when you open it up. At 60mph you virtually can't hear the exhaust inside the car. Again, it's only loud when you get on it, which I expected with two cats and two resonators forward of each stock muffler. It pops just a bit when you rev it and let off at idle, but when under load, you can downshift at relatively high RPMs and it just rumbles as you slow down. A mechanic at my dealership told me he put the GM performance exhaust, Borla mufflers, on a Camaro and it was NO louder than stock. The L99 needs no additional muffling.

P.S. - Very slight drone when in AFM. So just use M mode and tapshifters and it'll never go into AFM.