Mitch91Z28

I just installed a new magnaflow stainless muffler and cat converter and its not any louder than it was before... what gives? I searched

1991 Z28 'vert TPI 305 Factory manifolds, y pipe and cat back. magnaflow muffler and cat. All 2 1/2" pipe

89RS_82Z

iTrader: (2)

unless your stocker was rusted out and had holes, or was not really stock, it should be louder

headers would make it louder, and getting rid of the cat would help some

like to see a video or an audio clip, seems strange to me

TransAM Joe

iTrader: (6)

cat could possibly be plugged, if it's original I would replace it with a magnaflow unit.

webeeZ28

iTrader: (2)

Let me help you Joe

kkingsrulee

That's a nice looking iroc, I like the louvers.


And to whichever previous member said that it's because he has 2 1/2 diameter pipes running from the cat/muffler.


Notice it's a 305 he's upgraded the exhaust on, not a 454, so the 1/2 inch he's losing out on is definitely not hampering his exhaust flow, it's actually probably helping (the smaller diameter will help exhaust velocity out of the pipe) like blowing air through a smaller straw opposed to a bigger straw.

And it's not going to make a big sound difference either.


OP, were you running a muffler before you upgraded the exhaust?

Mitch91Z28

Yes I had a muffler before i upgraded. I believe i may have discovered the problem. I cant find my camera or i would take a picture. Right where the two sides of the y pipe meet the exhaust has been smashed (probably a speed bump) to about 2/3 the size it needs to be... I have ordered some long tube headers and a new over the axle pipe. I will build the new y-pipe When it all shows up I will see how it changes the sound

89transam*pearl

iTrader: (1)

The Magnaflows on my T/A get louder the more you get on the throttle, the Hooker headers probably have something to do with it though...

goldens98

Magnaflow isn't a loud exhaust until you get in the upper rpms. It will get a little louder over time. The muffler needs time to break in some.

89RsPower!

Yeah thats what all exhaust systems do.. even a gas powered weed wacker gets louder the more throttle you give it.. as you give an engine throttle more air and fuel go in thus more comes out causing it to get louder..

89RsPower!

That tiny little pipe is probably choking it off some, you should replace it with at least a 3 inch. It doesn't make much sense to go smaller than factory if you're trying to increase power, hell it doesn't make much sense to go smaller if you're simply trying to make it louder..

y84pauloflondon

He's got a 305 in it, and i believe(could be wrong) 2 1/2" is stock size. That 1/2 inch isn't gonna make that much of a difference! if his motor is mostly stock! Plus he's found a bad dent in the exhaust pipe, that could do it too!

customblackbird

iTrader: (15)

2.5" vs 3" is a noticable difference in flow. all the V8s 305 or 350 should be using a 3" system. even on a stock motor a 3" system will increase power over a stock 2.5" system, and its been track proven. most 305s didnt even have 2.5" system i though it was 2.25"? my 350TPI stock was like 2.5" i think.

the sound is prob not due to the dent unless its really blocking a bunch of the exhaust... its prob the muffler design. the stock type mufflers dynomax/flowmaster dont really increase noise all "that" much. a straight through design will make more noise. rip the muffler off and test it without a muffler if its louder and it will be then its the muffler design. the stock type mufflers are poop and i hate them. rip off the stock muffler and get a single inlet/outlet and run a single exit tube to the rear bumper. ull get alot better tone out of it.

goldens98

89RsPower what I was saying was that a magnaflow muffler or exhaust system is not loud sitting at a light like a flowmaster muffler. Magnaflow has no drone and they get louder in the upper rpms were flowmaster is loud all the time imo. The magnaflow will get louder over time. So keep your smart a_ _ comments to yourself.

y84pauloflondon

I have a Magnaflow Muffler ONLY, and all other pipes are still stock. When I did replace the stock muffler, I did notice a deeper sound, which was a little bit more louder(not by much) at ideal, but was much more louder and deeper when revving the engine compared to the stock muffler.

The reason I said it was a stock muff is that is had a AC Delco stamped into the muffler, Not a sticker, but into the metel itself!

iroc a 86 berli

[quote=MIDNIGHT-Z;4322327]damn dude, no reason to bash gays about loosing you louvers!

o.p, 305's dont run much compression. and loud 305's dont really sound good anyways, kinda like dudes that pull the baffles out on a honda shadows with only 750cc of displacment. they sound raspy and crappy. but are louder then shlt.

stock manifolds and y pipe dont help with gaining DB's, so dont be to down about it. axe the cat, and it will be a bit louder, but its un lawfull.

customblackbird

iTrader: (15)

the 86TA with a 307, stock TPI, ported heads and a compcam sounds fine with the 3"catback. there is honeslty no reason to believe that a 2.5" system will be better than a 3" system. exhaust velocities have compleley slowed down by the time it gets to the CAT let alone the catback part of it. He also stated that hes gona upgrade the 305 so why not get the 3" kit anyway if hes gona go larger down the road instead of buying another cat back later!?!

if you have any DYNO proof of a 2.5" system making more power than a 3" system then post it, but dont make accusations on something that you have no proof of. there are tons of dynos of 3" systems on stock 305s that can pick up .5sec in the 1/4 mile. CHP and carcraft have done it on almost any 305/350 camaro/firebird build.

Iroc a 86 berli is right too. Headers will increase Db over manifolds etc. and fartcan mufflers are loud bc they go from a stock 1.5" exhaust inlet on the muffler to a 3-4" outlet which is that RASPY crappy sound comes from. not a fan of dynomax never thought there stuff was loud enough or of that great a quality. so ditch the cat, get a REAL 3" aftercar exhaust and ull notice a difference. personally the single exit 3" systems like the flowmaster flow better than the dual exit ones, and u can swap out ANY single 3" muffler to get the tone u want. i like the welded Thrush mufflers and at 37$ a pop u cant go wrong.

the lovers are ugly so be glad they flew off lol.

Jimmy D

...that was funny

89RsPower!

I didn't reply to anything you said so keep your dumb *** replies to youself. As for mufflers "breaking in" they dont, they simply carbon up and rust out.

iroc a 86 berli

lol! my thoughts exactly!!!

oh and the thrushes sound great! maybe not in this video clip due to my shitty cam phone, had to wrap the mic part in a towel. sounds way better in person.

but they sound just as good as the flowmasters.

goldens98

89rspower when carbon builds up that's breaking in.People call it different things. Most muffler shops call it breaking it in.Search on this site other people say it also. Next a magnaflow muffler on a stock (key word is stock)is not going to be loud. Maybe 5 spd because you control your shiftpoints (upper rpms). If you want a 305 stock to be loud then you will need flowmaster, spintech, slp loudmouth ,tsp rumbler of course borla, open pipes. If you replace the magnaflow muffler with a flowmaster or spintech muffler it would be louder. The magnaflow does flow better. It's very close to the dynomax mufflers. They are not loud either. (both have Sound absorbing material). Flowmaster has chambers and spintech has a similar design but different sound. Spintech mufflers don't
have any drone to them.

mike sarmiento

i work at a high preformance speed shop and through my experience with magnaflow exaust is that they have to "break in" if you will just give it time and it should get louder and depending on which system you bought it may not make it louder persay it may just give it tone

89transam*pearl

iTrader: (1)

True, but the weed wacker never sounded like my Magnaflow at WOT ! Two thumbs up for Magnaflow"s catbacks...