...than stock?

It's some time away before I can even get to the fun stuff on my project (LT1 swap + a few mods), but I'm curious enough to ask now anyway. I've been told that if I want a nice sounding system that's pretty mellow at idle/cruise, but will scream at WOT, to go with a Magnaflow system.

Why my concern about the volume? Unfortunately, in Washington state, we may have some of the strictest laws in the U.S. regarding exhaust volume on anything less than 25 years old. We have one of those vague "anything louder than stock is illegal" laws that don't clearly define (in dB) what too loud is, but it's basically up to the cop's judgement if you get pulled over.

Now, that's not even the bad part. The real ugly part of it? Based on the info I can find online, an exhaust ticket counts as a moving violation in WA (I can't find a direct answer, but it's what it looks like). It's pretty obvious it's just a BS law to generate state revenue, but insurance rates are my main worry if worse came to worse.

Anywho, back to my main point. How loud is an internally stock LT-1 gonna be w/a few bolt-ons? is there anything I can do to keep the volume levels low enough to avoid unwanted attention? Thanks for any advice.

 

When I had my 305 and I threw on the flowmaster I felt like the whole world was watching me, although it changed very little in volume.

The magnaflow seems like what I'd use if I was in your shoes. Is dynomax still around?

Its going to be NIGHT AND DAY between a 305 and a full exhaust, bolt-on LT1. get ready for the extra attention, if your driving conditions warrant it.

 

Yeah, Dynomax is still around, I was considering a Dynomax set-up as well, but I'm told that they tend to be a bit on the louder side, and that Magnaflows are bit mellower, but offer some of the best flow available on an aftermarket exhaust (I do prefer the sound of a dynomax system, though they both sound nice to me).

And I figured an LT-1 is gonna be louder regardless, seeing how a bolt-on LT1 is making like twice the power of a stock 305 TBI (or at least close to). I am planning to clone my car into a Formula though, so maybe I'll have a bit of an excuse to be a little louder? . Either way, I'm generally a very respectful driver who follows traffic laws though (i.e, not the type to be revving at stop lights for races or doing burnouts everwhere I go, LOL)

What about silencer tips? I've heard a lot of import guys tend to use those to keep their setups quiet/close to stock volume (some are even quieter than stock, or so I've heard), and they're the ones that tend to be harassed the most by that law. Basically, I think the best chance I have of avoiding harassment is to go w/a set-up that looks and sounds as close to stock as possible, but I want the performance benefits of bolt-on upgrades.

 

From what i've heard from other board members as well as in my own experience, the dynomax system offers a sound that is closer to stock than any other system. However, i don't think that the dynomax system flows as good as magnaflow. the mangnaflow system offers a slightly better tone under normal driving, but screams at WOT. According to your description of how you drive, you won't be going WOT very often anyways. IMO, you should go for the mangaflow system.

1. Its stainless steel.
2. It flows VERY good.
3. It not really louder than stock if you drive normally, just a better tone.

http://www.youtube.com/watch?v=gfCxs...eature=related
http://www.youtube.com/watch?v=WwyxWxAX4CA

 

Well I have to respectfully dissagree about a dynomax being louder than a magnaflow, just from local experience of course. YRMV.

IMO the best catback that sounds good, be it a full exhaust LG4 or a bolt-on LS1, is the Aerochamber.

OP, are you doing headers at the same time?

 

Mine wasn't made by Magnaflow, but uses a bullet Magnaflow muffler on mandrel bent pipes.

At part throttle & cruise, it is very quiet & won't throw any red flags. WOT is another story!

My Videos

 

Alright, so I think I've figured things out for the most part.

Everyone is saying that for the best performance gains that I want, with the least increase in volume at idle/cruise, to go with the Magnaflow system. I've watched various youtube clips, and as you all are saying, it mainly just gives it a better tone than making it much louder. so I've decided I want a Magnaflow cat-back system, but I still have some other questions..

- What are some good headers to go with? (Keep in mind they must be smog-legal).

- From what I've looked into, the Magnaflow system I'm looking at is just kind of a general V8 third gen fit, and will work on either a 305, 350, LT-1, or LS1, but I'm just making sure that this is in fact, true? (Say, if I decided to get exhaust done before my engine swap). But I'm wondering, would headers that fit on a 305 work on an LT-1/350 too? or no?

- Lastly, if worse came to worse, would the stock exhaust system from a 305 TBI car be usable on an LT-1/350? Though I'm doing what I can to keep this car legal, there's still risk involved with our asinine laws, so in a worse case scenario, I'd have to throw the stocker back on to beat a ticket in court. I wouldn't care about a small fine normally, but when equipment violations = moving violations (translation - complete BS), and your record is clean, you tend to want to keep it that way

Maybe some of you might think I'm being too paranoid, but I'd rather play it safe than sorry in this state. Though from what I've told, cops mainly go after the imports, or at least much more so than muscle/trucks. Though I suppose loud cannon exhausts and tinted windows w/stickers just screams "boy racer", and is asking for trouble!

 

hooker 2055s are what you want. emissions legal shorties with an AWESOME factory routed 3" y-pipe. I literally chopped the LT's off my camaro because I was tired replacing the exhaust every other day.

stock exhaust is 2 1/4. it'd probably have the same effect on a future LT1 as pulling two spark plugs.

 

93-97/LT1 cat backs are a virtual drop-in, except for maybe some hangers needing to be changed. 98-02/LS1 will have to be modified a bit to hook up to the Y-pipe plus possible hanger mods.


Define "work".....Will it bolt up & be driveable? Yeah. Will it be more like pulling 2 plugs (as Tobias05 mention)? Kinda. It'd get you to pass at least, then you could throw the Magnaflow back on. Or just have a shop put flanges on both ends of the Magnaflow muffler & fab up another stock-style/quiet muffler to put in its place for inspection/beat a ticket time.

 

the LT1 exhaust port is also a D-port. IIRC 305/350 headers will bolt up, but they wont flow as well. i cant seem to find them but someone makes LT1 swap headers for a thirdgen...

 

i have an LT1 and a magnaflow catback that was made for a 93-97. had to add about a foot of pipe to connect to the cat. i also have Hedman shorty headers and y-pipe that's made for the thirdgens and D-port heads. i have a catco high flow cat, so the magnaflow is really mild cruising around, and not really even loud wide open this way.
I also have an electric cutout right before the cat in case i want to be obnoxious.

really, the idle is nice and sounds similar to a stock LS1 ideling, but slightly louder...not enough to notice unless you have them side by side. cruising in town is similar. nothing special to notice, but still slightly lowder than a stock V8 F-body. i'm sure if i didn't have a cat, it would scream wide open, but it doesn't really even do that...maybe my hearing perception is off due to all of my friends' annoyingly loud cars, and the fact the noice is traveling away from me. i guess i need to let someone drive my car once so i can hear it myself.

 

Hmm, so it sounds like putting the stocker back on w/a 350 or LT-1 will really choke it up, but that it'd probably be easier to just tweak the muffler or throw a different one on than to swap out everything in a worse case scenario?

Also, I'm a bit of a n00b with exhaust stuff, so what does a D-port exhaust port mean? And dans89, that'd be super rad if you can find those LT-1 headers for a third gen you're talking about!

And one more thing, I keep hearing of people using 93-97 style LT-1 exhausts on their third gens in this thread, but this is the system I've been eyeballing that's supposed to be a specific third gen fit. Shouldn't this be easier?

http://www.jegs.com/i/Magnaflow/642/16829/10002/-1

It's tempting to look into before my swap, since it looks to be compatible with both 305's and 350's. If it's compatible w/my future engine plans, than why not, right? And to my knowledge, 350's and LT-1's pretty much use the same-style block/share the same dimensions, even if they're pretty different interally?). Anything I can use to help that stupid 305 TBI and still use later on is always a plus!

 

i used the 93-97 (15620) system only because i found one on sale at the time. mine is 3 inch, just like the one in your link. the dual exits are really 2.5 inch that flare out to 3.5 inch, but it's not a problem. i plan on getting rid of my tips and just using 2.5 inch turndowns, similar to factory exhaust.

the LT1 heads have D shaped exhaust ports, so I used D-port headers to match them.

 

My magnaflow cat back is not loud at all, it's a low tone not raspy like the Flowmaster garbage. I've had flowmaster, dynomax tubro, and magnaflow to judge from.

Dynomax turbo muffler flow great and sound too. Good cruising tone, not over powering (eg. can still talk w/o yelling), but roars when you floor it. It's much louder then my magnaflow (my z28 has dyno, RS has mag) but the mag exhaust has manifolds and a cat.

The magnaflow is the way to go IMO.

Just to put this out there because I never seen anyone say it. The I pipe on the mag exhaust has 2 different buts for the cat; ones 3" the other is stock for 5.0 (can't recall) but the pipe it's self is not 3" its 2.75" and flares out to 3" as it goes to the over axle part.

 

Mine is a LS1 catback, put on by the previous owner, who said the shop charged more to install & mode the y-pipe connection, than the system even cost.
http://www.texas-speed.com LS1 catback

They sell the SAME kit for use on a LT1, so I suspect he just got ripped off by that shop.
http://www.texas-speed.com LT1 catback

 

i purchased magnaflow catback for my 89 iroc, love the tone. just wish it was a little louder. but yes if you get on it it does become louder. a family member had flowmaster and was louder yet the tone wasn't as good plus theirs wasn't stainless so it rusted. personaly i am going to replace the cat with a magnaflow one as well. if you get it done before me let me kno if it sounds better/louder

 

http://www.youtube.com/watch?v=n-jjCQxvJHQ stock vs magnaflow
clip helped me in my choice in exhaust system... now i just need to get the funds