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73-87 Chevy _ GMC Trucks => Performance => Exhaust => Topic started by: p7387 on November 12, 2015, 09:42:24 pm
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1987 305 2wd short/fleet
its time to replace the exhaust and i was going to bring it to a meinike shop where a dealer friend of mine has a wholesale account. i am looking to put dual exhaust (without any catalytic converters) exiting from the back.
(any opinions pros or cons on side exit vs rear exit?)
in terms of sound i am looking to acheive something moderate and healthy, not crazy aggressive but not too tame.
some of the names i have come across are FLOWMASTER, MAGNAFLOW, AND TURBO but i have no personal experience with any.
i would hope to do this work within a reasonable budget, any opinions will be appreciated.
thanks
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So are we talking full on dual exhaust? I would personally say that it is entirely unnecessary to have two exhaust pipes on an assumingly stock 305. I can't find the link atm, but a single 2.5in exhaust is good for a ton of horsepower. Like more than the average person is gonna end up with under the hood (if youre staying below 400 or 500HP then you are more than good). Muffler is a good idea tho and it really just depends on how much you wanna pay. I was gonna pick up a Flowmaster 40 series eventually as they give good sound out of a 350, but it's not exactly gonna increase performance. If you want to increase power, then youre better off picking up a bigger intake manifold or something for a bit more money.
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my exhaust is rotted and needs to be replaced anyway.
your point about putting the effort into a 305 is well taken though it does make practical sense.
while i would hope a dual exhaust might help performance a bit its not my primary goal, nice sound and aesthetics are.
with that objective in mind was hoping for opinions as i have no experience in this area.
thanks
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I have a 305 and my truck had full duals when i got it. It was also rotted out, i replaced with full dual with no cats of course. Its a little on the loud side, but runs well. I am now doing the ex manifolds with the heat riser valve included. There is a post about backpressure you may want to see. I dont fully understand backpressure and how much we need, but i know its important. I'm still thinking of how i can quiet my system a little.
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a few thoughts of mine:
1) If you like true duals, then by all means proceed. However, you may want to read this first:
http://www.castheads.com/manifolds-carb/exhaust-manifolds/2-into-1-exhaust-collector-systems/
i used to think that adding true duals automatically meant more power and mpg, now i'm not so sure.
Now, if you like true duals, then that should be the deciding factor because i don't think it's going to make a ton of a difference in a street driven car.
2) You asked about muffler brands:
i was running dual flowmasters 40s (a true dual system) up until recently before my engine swap. It was too loud for my tastes, but i'm different because i'm not into noise for a daily transportation vehicle.
Now i run a single exhaust with a supposedly stock muffler and even with the 4.3, it's just as loud as the 350 and 305 with duals!
3) It was mentioned that "backpressure" is important. Not so much backpressure, but i think velocity is important for exhaust.
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If you ever plan to replace that 305, run a 2.5" dual exhaust, L&R 90° exits past the axle sound and look the best. Flowmasters sound great. Stay away from cheap turbo mufflers or glasspacks.
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^+1 on what Vile says. I have this setup on my truck. I had aluminized exhaust put on it back in 1987 and it still looks solid. I replaced the mufflers with 44 Flowmasters. I noticed that the exhaust throws more condensation out while warming up now due to the larger diameter pipe. I also put a long stainless angle cut tailpipe on mine as well.
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I was told there are three reasons why my truck is a bit loud.
1. Dual exhaust
2. No cats
3. My pipes are larger than normal stock
When this system rots out in 10 or so years, i'll probably go to single normal size pipes and a high quality muffler.
I coated it with high temp paint and high temp grease. It'll be a while...
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I'm still thinking of how i can quiet my system a little.
Stock/oem mufflers.
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If you want yo run dual exhaust on a daily driver 305, check out Flowtech Afterburners. 2 in pipes without a cat would be very crisp.
Sent from my SM-T217S using Tapatalk
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That'd be fine by me, but like i says, i hate rust and corrosion so much, it would be a while before i need any exhaust parts. I coated everything with high temp paint and high temp grease. Waste of money to do anything now. But i'll keep those flowtechs in mind.
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thanks for the advice
as vile suggested i would go with the left/right exit after the axle setup.
i did some research on the flowmaster, jeggs and summit sites, based on my truck specifications
(1987-R10-305-shortbed) they were showing limited options
Super 40 Muffler - 2.25 Offset In / 2.25 Offset Out - Aggressive sound
40 Delta Flow Muffler Offset In/Offset Out: 2.5
Super 50 Muffler - 2.50 Center In / 2.25 Dual Out - Mild Sound
i would prefer the single out tailpipe offered in the 40 series and not the double out tailpipe of the 50 series, however the "aggressive" specifications of the 40 series concerns me, i would like it so sound nice but not so loud that i would have a headache after a 3hour drive. also i see the price point of these is between 95-130 dollars.
any other alternatives keeping budget and moderate sound in mind
thanks for the input
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Good plan.
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Going for a stock look I like duals exiting at 90 degrees behind the rear tires with a crossover pipe up front.
Muffler choices are limitless. Quite factory style Walkers for me.
If like me you find yourself having to remove and reinstall sections of the exhaust system to drop the fuel tanks, transmission, or transfer case, use band clamps! They cost a bit more than U-clamps up front but pay for themselves the first time you take the exhaust system apart.
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Good point
I only have the one tank setup on the drivers side
Is there any type of configuration that will not interfere with any future transmission or fuel tank servicing down the line
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Use band clamps and if needed you will be able to disassemble / reassemble the exhaust system at-will in minutes.
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If you want quiet locate the muffler as far back as possible and install a crossover, I ran the exhaust temporarily until I could get it on a lift and had the mufflers under the cab and dumped just before the rear wheels and it was way too loud in the cab, now I have a crossover just after the transmission crossmember and mufflers located just behind the cab with 90s behind the rear tires. Now when we built this on a lift we left out the crossover due to time constraints and added it next day, and it was noticably quieter with the crossover. I used the dynomax kit for our trucks (2.25") but had to modify it to work with my headers and I used thrush welded mufflers.