I know...many exhaust threads, but why not start a new one right???

Currently running 1 3/4" LTs/ORY/into a stock WS6 catback with cutout and Hooker Aerochamber in place of stock muffler.

I like the sound the aerochamber makes. I like the cutout for the track. However, I really want true duals.

So...i've read for years that 1 single 3" outflows dual 2.5". I'm not an engineer so I don't really understand how 5" of total flow doesn't outflow a single 3" but its been said over and over.

I'm on 28's now so running a TD setup would be more doable w/ more ground clearance.

Any suggestions? I want to keep it legal w/ mufflers (not sure if bullets count as mufflers in true street drag classes).

Thanks ahead of time!

 

If you do a little math, you will see that a pair of 2.5" pipes do not equal 5".

 

Ok alan, rather than give you flack about your math, ill try to give some helpful input. if you are set on true duals then it will probably be difficult to change your mind at all, but here is what id do, and am doing. (already have the parts) Id get some stepped headers with the 1 3/4-1 7/8 primaries and 3" collectors. then id go to a Mufflex off road Y, and 4" catback with magnaflow race muffler. have spoken to many LTx guru's including Ed Wright and Lloyd Elliott, and both of them told me that this is right in line with the flow of true duals and will give me much better ground clearance. Since my car sees ample street duty as a DD, this was clearly the way to go for me. plus the tail pipe tucks up nice and is barely visible (if any at all) from behind the car. kooks and LPP both offer a good stepped header, and honestly i can see no visable differences between the two. I bought some kooks, but that is before i heard about LPP. looking back, i probably woulda bought the LPP since they run about 475 and the kooks were MUCH more than that. just my $.02

 

gonna have to ask you to explain this to me as well. if you take 2.5 x 3.14 (PI) you get 7.85 sq inches. you multiply that by 2, and you get 15.7" squared. now if you take 5" and mulitply that by 3.14, you get 15.7" sq. so how does two 2.5" pipes not equal the same flow volume as one 5"?

 

From LT1engine.com...

"The most common question is 2.5″ or 3″ true duals, and here is your answer.
A 2.75” (stock) single system is good for a 310hp engine with zero loss…
A 3” Single system is good for a 370hp engine with zero loss…
A 3.5” Single system is good for a 503hp engine with zero loss…
A 4” Single system is good for a 657hp engine with zero loss…
A 2.25” dual system is good for a 457hp engine with zero loss…
A 2.5” dual system is good for a 513hp engine with zero loss…
A 3” dual system is good for a 812hp engine with zero loss…"


If it were me...I would start by swapping the headers out for a 1 3/4"-1 7/8" stepped or 1 7/8" full length. I would then back it with either 3" TD's or a Mufflex 4" single system. You are limited with muffler choices with the Mufflex system where as you have all the options in the world with the TD's. I vote for the TD's for that reason but either way you will be letting that 398 breathe properly.

I wouldn't worry too much about ground clearance with the TD's. I have 2.5" TD's and I have not yet had any issues with them and I was lowered 1.25". My car is now slammed with my new adjustable drag coilovers and now my ground clearance is minimal but considering the very small amount of driving I do I am not concerned.

Also, I don't know why Bullets wouldn't count as mufflers. They are a muffler and they quiet the car down over no mufflers but you could always check with them to make sure. Anyways I run them and like them alot myself.

EDIT: It's pretty nice out today I'd be glad to take a video of the Bullets if you wish to hear them.

 

i'm liking this info...and i'm not set on anything, so good stuff!

and my disclaimer was I knew i didn't understand the math, so i'm not offended. Glad to see your thoughts.

 

mfflex may only give 3 muffler choices, but if you have looked through a magnaflow race muffler, you will see that you look into a 4" hole on one end, and see 4" of light on the other. it is quite literally straight through! here are a few examples of mufflex systems..

http://www.youtube.com/watch?v=RDANR7iLmdA

http://www.youtube.com/watch?v=bKsIUOJPXCQ <this one they didnt put the tailpipe all the way up like its supposed to tuck though.

and if you really wanted, you could add a 4" cutout even. lmao. that would be rediculously loud though.

 

great info and YES, please do post some evidence!!

 

N/A 383 in a third gen auto car. this is my best friends ride, aka the crew cheif. i love the sound. this car made me buy mufflex.

http://www.youtube.com/watch?v=ID90iRPuRkI

this car has a mufflex with a dynomax ultraflow. basically the same design at the magnaflow race muffler, but he picked it up to get rid of the spintech muffler.

 

Going by this, i have alot to gain with my new headers and mufflex. seems my TOTL exhaust has been really holding me back. by the way, that is not being sarcastic. was actually being very serious.

 

the LPPs look real nice...wondering about ceramic coating or just going bare stainless like I did on my Kooks on the V...

found the mufflex site w/ f-body stuff...boy have they gone up in price since in the last 7yrs...yeah, its been that long since i've bought exhaust stuff for the bird.

 

yeah, not too easy. and not alot of people use the mufflex with magnaflow because they dont like the single outlet. i love it. you can find alot of mufflex 4" on youtube with the spintech or flowmaster crossflow mufflers. those mufflers are too restrictive for me. like i said, my boys IROC has mufflex on it, and i love the sound, and his throttle response is so snappy its crazy.

 

Get you a merge, a small stick of 4 inch and put a 4 inch Magnaflow under the floorboard with a turndown at the axle.

 

Nothing wrong with doing bare stainless... What most people don’t think about when dealing with coatings though is the reduction in temperature! Stainless is a great product to start with and will reduce the chance of rust and due to the nature of the metal will assist in lower heat numbers under the hood. You couple stainless with our coating and you can reduce temps up to 300° or more, not to mention the power gain when coated 100% inside and out. This will reduce the turbulence in the exhaust gasses and allow them to flow smooth in return allowing the engine to breath deeper.

 

so whats that cost for a set of kooks long tubes?

 

AH YES, the newly rejoined sponsor speaks!! I've enjoyed several JetHot coated headers in the past (ls1 cars and BBC headers). Didn't do it on the V because basically too many test showed the heat didnt affect it like many, but the LT1 would certainly benefit. I will certainly keep that in mind as underhood temps on this stroked LT1 is a concern for me for sure.

Thanks

 

i like simplicity!

 

Hook the merge to your Y pipe. You can get pipe and turndowns cheap at the local 18 wheeler dealer.

I got all my stuff from these guys.

www.fulllineexhaust.com

I can uncap my car at the track and it runs the same as capped up. I have a full 4 inch Mufflex with a Maganflow muffler under the rear. But I am thinking of doing what I told you to do.

 

I took two videos today but apparently an LT1 is too much for the microphone of a brand new camera, even from 20 feet away! I don't have my old camera around otherwise I'd just use that.

 

I have a 398 too and plan on ditching these massive *** hedman longtubes for some 1 3/4 and a traditional y-pipe with cutouts for the track. Street will be a borla catback setup.

Tony.