2 exhaust systems...

[Guest bluex_v1]

I'm am totally torn as to what exhaust system to build right now...and wondering if either would actually work out. I've spent about the last week reading through every chevy post starting back on page 102 since it had lots of generic stuff in there I guess since before the Exhaust board was created. Anyway, these are the major facts I have gleened from it:

 

-Many v8Zs run dual 2.5" into 3" singles and are content with them. Those that have switched back to full 2.5" duals or gone up to 3.5" single pipe have noticed little or no performance change

-A dual 2.5" into 3" single system should not be any more restrictive than a full dual 2.5" up to 400HP output.

-Flowmasters will drive most people nuts because of the way they drone on the highway if the car is a daily driver.

-Dynomax turbos are generally accepted as the best performance muffler that can still keep the commuter sane.

-Cherry bomb glass packs are or quickly become more restrictive than just about anything

-The only way to get a 3" system quiet is to use two mufflers in series, such as a bullet style race muffler/resonator in the tunnel with a turbo muffler at the back

-If you use multiple mufflers, you should use the straight through types.

-If you use dual mufflers of the same size, they will resonate against each other and and buzz like crazy (Is this still true if you have an X or H pipe before the mufflers??)

-in a 3" Y system, even with a bullet and then a flowmaster on the back, it is still loud

-3" Y systems are lighter and easier to install and maintain and allow better tranny access.

-Y pipes and crossovers should be installed as close to the header collectors as possible

-A Y pipe or X pipe will smooth out the exhaust note significantly and quiets it slightly

-Primary pipe from the header collectors to the Y or cross over pipe should be as close to equal lenght as possible.

-A 3" system will lose ground clearance because it hangs down .5" lower than a 2.5" and it can also not be tucked up into a tunnel as easy as a narrower 2.5"

 

Design constraints: This will be a daily driver 5.0 with a T-5. I like to listen to music on highway trips. A loud droning exhaust won't work for me I'm sure. I will likely also lower the car an inch or two in the future. I want to build the system myself because I want to learn how to do it and get some gas shielded welding practice.

Here are the two systems I am thinking of using:

Please give me input on the pro's and con's

 

System A:

Flowtech block huggers

Dual 2.5" pipe back to the T-5 crossmember

Flowmaster dual 2.5" to 3" Y pipe right behind T-5 crossmember with the 3" Y outlet welded directly into a 3x9.5x16 3"oval center-in/offset-out Spintech tucked up under the driveshaft with brackets welded directly to its case. Run 3" oval pipe from the Spintech's side outlet, under the rear arms, and then up into a 20" case 3" in/out Dynomax super turbo mounted in the stock location.

 

System B:

(you may need to refrence one of Terry's pics here 289 with T-5 for this to see if it would work or not. As a side note, I believe I can get a pan that has the rear of the front sump probably 2-3 inches further forward than his is there)

Flowtech blockhuggers

2.5" dual donut peices and J's to a 2.5" X-pipe with a compact squared off shape that will be positioned in the gap between the bellhousing and the rear drop of the front sump. (The X may have to sit in there kind of nose up and the routing to it and out around the bellhousing would no doubt be insane...you can bet your ass I'd get that whole assembly ceramic coated ) Then with the 2.5" duals running into the tunnel with T-5, I'd have plenty of room to put some long 4" bullet muffler/resonators in there with 2.5" pipe routing up and into a pair of Dynomax super turbos side by side with some spare tire well mods (but hopefully still enough to give me room for one of those ZX donuts)

 

I am guessing the costs between the two will be about the same when you factor in A requires more expensive mufflers, but only two of them, but also a Y pipe and some 3 inch oval pipe, vs B which requires more but cheaper mufflers, an X pipe and probably more donuts...I think if both of these are actually feasible ideas that I can get to work, either would be equally sweet to have. I think the duals would be harder work, but dare I say, it might be a system to rival Pete's But, then how hard is it to route 3" oval pipe up and into the stock muffler area and then get it to mate with a 3" round muffler inlet?

[Lockjaw]

Those "Blowmasters" will be way to loud, and they don't flow very well anyway. A walker super turbo muffler is fairly quiet, I had a 3 inch cat back on my last truck, and it was quiet, but just slightly deeper than stock.

 

You need a muffler with packing to be quiet. A straight thru is nice but louder. I have a Hooker 3 inch maxflow on my ZXT with 3 inch mandrel, and it is pretty quiet, doesn't drone on the interstate, but it talks to ya when you hit it.

 

I hate that droning noise, and the best advice I could give you is to use the super turbo. I think it offers good flow and quietness.

[Guest bluex_v1]

yeah, I'm definately in agreeance with flowmasters being too obnoxious, which is why neither of the two systems I'm considering will use them . Both of the two systems I'm considering will incorporate at least one super turbo.

I guess my specific concerns are:

would I be able to get away with putting an X-pipe between the bellhousing and the oilpan sump without all of the crazy tight bends to it from the headers being too restrictive?

Would there be any weird turbulance issues or something if I welded the flowmaster Y pipe directly into the spintech?

Would putting a 3inch super turbo after the spintech net me any real additional sound decrease?

[Guest Carlissimo]

Why are cherry bomb type glass pack mufflers considered too restrictive ? They are basically straight thru pipes with no change in direction of the exhaust flow.

[Guest bluex_v1]

I don't know...this is just info I took notes on as I read through these forums...based on statements of people more respected and experienced than I.

My guess though, is that, at least once the fibers degrade or pack together, the rasp like innards of the muffler must cause vortecies that disturb the free flow of gasses. Anyway, several members have posted this and some noticed increased performance after dropping their glasspacks for straight pipes or supposedly more restrictive turbo type mufflers.

[Cruez]

I put a "cherry bomb" type muffler to quiet mine down enough to use a cell phone on the car, and that muffler drastically lowered the HP, I'm sure....seat of the pants dyno even told me that.......it is coming off soon.

[pparaska]

I really like the 2nd system idea. The X-pipe up front is supposedly where it should be.

 

Resonators in the tunnel, if you can get them to fit up tight, is a definite plus. Any muffler hanging at the back of the car will be louder than needed. Mufflers need tail pipes to muffle well, in my experience.