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Discussion Starter · #1 · (Edited)
Ok I was driving my 93 trans am lt1 yesterday when all of a sudden I hear a bang and dragging noise. My muffler broke free from the pipe that comes from the front of the car so I am in need of a catback exhaust at the least. I would prefer to put on true dual exhaust if I can.

What I'm unsure of is what size tubing to go with 2 1/2" or 3"? I'm not building this myself but I want to know what will be needed to get this done properly. Any suggestions for mufflers that would sound awesome? Can I get away without catalytic converters here in ny? If i need the cats any recomendations for those?

I already have headers on there so for now I'm thinking I'll leave what I have on there but if funds will approve I may buy some new ceramic coated or stainless longtubes as the ones I have are just painted and look like they need new paint as it is. Basically I'm looking ballpark a price for the dual exhaust setup vs catback exhaust. No sense spending $ on catback if dual exhaust would be a better choice and reasonable cost.
 

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Im in the process of building up my true dual system

http://www.ls1lt1.com/forum/showthread.php?t=45978

Im going to run 2.5" 304SS pipe with mandrel bends throughout.
I have Magnaflow metallic spun cats
Sweet thunder chambered mufflers (304SS also)
and Corsa clones outback.

Right now, barring no extra expenses, I will have to spend 1200 to do my entire exhaust.

This includes oxygen sensors, labor, and new v-band clamps for my headers.

So its not cheap. BUT rebuilding my y-pipe was gong to cost close to 2/3rds of that so I just decided the extra 1/3rd was worth it.



To answer some of your questions, it depends on what you are doing to the car, do you need the 3in pipe?
cats are required by federal law on all cars originally equipped with them, BUT we are already breaking the law by moving them from their manufacturer location
 

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Discussion Starter · #3 ·
What your doing is quite similar to what I want to do. My motor has been built I haven't gotten any verifiable data as to any hp or torque numbers just a cpl educated guesses to aprox 400 hp. Do I think I need a 3" exhaust for flow purposes no not really but I only want to do this once and want to be sure if I improve things motor wise the exhaust won't be the restricting point. I don't mind spending $ on my car but I don't want to spend $ redoing something I've already done. So considering I have to spend $ on exhaust I figure I may as well go out and do it right the 1st time. I also should mention that the intention is to keep it street legal
 

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What your doing is quite similar to what I want to do. My motor has been built I haven't gotten any verifiable data as to any hp or torque numbers just a cpl educated guesses to aprox 400 hp. Do I think I need a 3" exhaust for flow purposes no not really but I only want to do this once and want to be sure if I improve things motor wise the exhaust won't be the restricting point. I don't mind spending $ on my car but I don't want to spend $ redoing something I've already done. So considering I have to spend $ on exhaust I figure I may as well go out and do it right the 1st time. I also should mention that the intention is to keep it street legal
if you have plans to get faster later on, just go with the 3"
it will hinder your bottom end power though

I think it would be smart to do it just once as well.

if you are keeping it street legal, just put the cats back in, those magnaflow spun cats flow really well, and the metallic matrix holds up well compared to the ceramic ones.
 

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Discussion Starter · #6 ·
I've looked through that thread already good info and pictures help alot the sound clips unfortunately don't help me much as I mostly view and post from my iPhone so sound isn't the greatest.

I do want that nice loud tone from my exhaust and I have admit the way my car sounded with the old exhaust was sweet. Right now I just going to start pricing the stuff to do it both dual and catback kits and base my decisions from there.
 

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Discussion Starter · #7 ·
How much low end do you think I'll lose going to 3"? When my muffler fell off yesterday I noticed a drop in power. Will it be as drastic as the way it is now?
 

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How much low end do you think I'll lose going to 3"? When my muffler fell off yesterday I noticed a drop in power. Will it be as drastic as the way it is now?
thats kinda the grey area of the mystic art known as pipe sizing.

it would be tough to give you a specific answer, it really is dependent upon your system
 

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Discussion Starter · #9 ·
thats kinda the grey area of the mystic art known as pipe sizing.

it would be tough to give you a specific answer, it really is dependent upon your system

Yeah I was thinking that would be the answer I got to that question basically if it's such a minor drop that ya wouldn't really notice it unless you compare before and after dyno numbers or track numbers I probably wouldn't mind so much. But if the difference was so noticeable that you can tell that you've lost power just by driving it (which is what happened when muffler fell off) then I'd probably regret it.

This is the sucky part of where I'm at I just bought this car like 2 weeks ago so I didnt build the motor the po didn't build it it was a cpl owners back. So the only thing I know about the motor build is what I was told and what I can see without ripping it apart. I do know it has msd 6al ignition, msd spark plug wires, roller rockers, lt4 intake, holley throttle body, I was told a mild cam and you can hear the lopey idle in the exhaust, ram air has been added and functional.
 

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Discussion Starter · #10 ·
I do have receipts for things done to this car but unfortunately whoever building and buying this stuff didn't write down specifics like cam specs and some receipts are just part #'s with no way of knowing what they are without looking stuff up. So I'll have a receipt for something for $250 and only thing it has is a local shop name and part # sometimes crappy discription and labor charges.

I did look up and price stuff to build a dual exhaust setup the way I want and it looks like it's going to run a little over a grand to $1400 tops. And this is probably a bit higher then actually what I need as I priced it as needing 30ft of exhaust piping which I think is a bit much. It seems as far as catback exhaust goes I've narrowed it down to magnaflow which is like $450 from summit racing. When I narrowed my search down in summit with te things I wanted it came up with magnaflow and corsa which was over $1000 so I eliminated that due to cost if I'm spending a grand I'm going dual.
 

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Discussion Starter · #11 · (Edited)
Ok I've thought about this for a while now I'm going to bite the bullet and do the dual exhaust but I'm only going to do 2.5" tubing not 3" as I don't want to lose lower end power. Going to go stainless steel front to back. Anyone have any suggestions for mufflers and cats? I have been looking at borla and flowmaster but open to other possibilities. Any brand I should stay away from? I like a loud exhaust so I'm not picky with mufflers being too loud
 

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Ok I've thought about this for a while now I'm going to bite the bullet and do the dual exhaust but I'm only going to do 2.5" tubing not 3" as I don't want to lose lower end power. Going to go stainless steel front to back. Anyone have any suggestions for mufflers and cats? I have been looking at borla and flowmaster but open to other possibilities. Any brand I should stay away from? I like a loud exhaust so I'm not picky with mufflers being too loud
Im going with a 304SS system also, with Magnaflow metallic spun cats, and Sweet thunder chambered mufflers (like GMMG)
 

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And bullets IMO sound better than glasspacks, but the chambered mufflers sound good also
 

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Discussion Starter · #15 ·
Thanks for the link I'll check that out later. I am going to stick with 2.5" pipes for now as I think the 3" will be too big with what I got now. I would like to go bigger on the motor at sometime but I think after the exhaust is done I will be waiting a cpl years at the least before I do anything with the motor. I want to get the exhaust done and plan on next winter/spring upgrading the suspension and subframe connectors. I know a prev owner has upgraded to Polly bushings throughout the car but haven't gotten to take a good look underneath to see if he's upgraded anything else. So Considering I don't have a lift I want to see if whoever does up my exhaust will either check that out for me or let me take a look to see what has been done suspension wise. The plan is exhaust as it needs fixing now then suspension and then motor and then body and paint. The plan is to get this stuff done and still allow myself plenty of time during the summer to enjoy the car
 

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Discussion Starter · #16 ·
3-3.25" would be a good size on a catback (3.25 would require that you make your own)
2.5 is plenty big up to about 460 horses with a dual system
Check this page out it will help a lot with your decision
How To Calculate Muffler Size and Exhaust Pipe Diameter | Exhaust Videos
that link is helpfull and a good read thank you. i dont think im at 460 horses right now. i know my motor is built but only mildly. the best guestimates and assumptions (yes i know thats no true indication of power) is 400hp. once i get this exhaust fixed i want to go have it dyno tuned as i think my car will benifit from it and i will accurately know what my car is pulling hp wise.
 

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U don't need cats in ny. Yes federal law requires them but 99% of garages here will not inspect it that thoroughly. I have Bbk stainless shorties with 2.5in stainless y pipe into 3 inch single pipe with flow master with dual stainless tips. Car is very loud. Mine also is 93 z28 hardtop has the dark green/gray metallic paintjob which from what i hear is pretty rare.long tubes and some dynoport race mufflers would shake the ground. I plan on going with an electric cutout also for strip use only :lol:
 

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I wish I could say my car was around 400 lol i would be lucky to have about 300 at the crank, maybe some day though
 

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My 93 should be making at least that at the wheels. Was in the process of having a11.5 to 1 355 built but my machinist was killed in a car acciident last friday so now im buying a fully forged 396 short block from golen engines in nh. A set of ai trickflow heads and were gonna make a custom remote mount turbo kit as i have 75% of what's needed for the kit as . Also have a hughes 3500 stall with lockup and saving for a performabuilt 4l60. If it doesnt make 400 at the wheels ill burn it too the ground.Sorry bout the hijacking but im blitzed lol
 

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well considering an stock fbody LT1 4l60E makes only like 220-230 at the wheels, mine probly is around 250. Thats really just a guess though, cus ill never know if the previous owner messed with the internals or not unless I take it apart (I find it weird that he installed a shift kit but nothing else, not even a CAI)
 
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