Exhaust question (I searched, I promise!!)

SVXMAN2001 · #1 11-21-2006, 09:56 AM

So i've been contemplating a new exhaust for quite some time, and after reading through the vast amount of information this is the general concept that i've come up with is to stay with the precats into a 2 - 1 hi flow cat, into a resonator, then muffler...

I am looking to have a freer flowing yet still stock quiet exhaust.

There has been much talk about the resonation that occurs with replacing the precats with a y-pipe hence why i will be keeping the precats, HOWEVER, i am assuming the precats will need to be cut (after the stock resonators in the precats)...my question how far AFTER the resonators should the piping on the precats be cut? 3,4,5 inches? does it even matter?

Also is a resonator necessary AFTER the primary cat?

Also what type of muffler (is magnaflow the best? what series for the most quiet?) What type of resonator? How much larger in diameter should i go in the piping?

I know there is a lot of questions in here, but your advice and input are greatly appreciated...

Thanks, Chris

TomsSVX · #2 11-21-2006, 10:03 AM

you can have mine when I am done with my new one... its not quiet but sounds really good on a stock car

Tom

mikecg · #3 11-21-2006, 10:13 AM

Just had some issues with my setup. First, the precats dont prevent the resination. The resinator does that. In my opinion the biggest increase in flow can be had by replacing the sections between the exhaust manifolds and the outlet of the y-cat. If you accually look at the pipe it is tiny. Hears what I recommend:

Come off the manifolds with 2.25 inch pipe, through 2 highflow cats. Y together. From there you can run stock pipe back to the muffler and use a single in dual out muffler. If you want to keep it quiet I'd use something along the lines of a "Turbo" muffler. Stay away from both flowmaster and magnaflows. They will make your car louder. The resinator is key to not getting the resignation though. So what ever you do, dont delete it out. You may be able to get a high flow one, but I havent tried one of the high flow resinators and dont know if they will illiminate the resination as well as one with baffles in it.

I've been messing around with my exhaust off and on for 4 years now, and that is what my exsperience with our cars tells me. There are some other folks around with exsperience on different setups. I'm sure they also have some suggestions to add too.

SVXMAN2001 · #4 11-21-2006, 10:28 AM

Mike, so are catalytic converters similar to resinators? Essentially i'll be recreating the stock system except that the piping will be larger and there will not be a resinator AFTER the primary cat?

With your recommendation I'll have three cats? Won't that increase restriction, or will "hi flo" cats negate that?

mikecg · #5 11-21-2006, 11:06 AM

Resinators are more like a muffler. Cats are designed to catch excess fuel in the exhaust and burn it off so it isnt released from the exhaust and polluting the air. That is why they need to be fairly close to the manifolds and have to heat up before they work. The Pre-Cats are the same thing as a regular Cat I think they are just a little smaller.

I was taking about removing all three cats on the stock system and replacing them with 2 hi-flow cats and a Y-pipe. Basiclly your removing 3 highly restrictive standard Cats and replacing them with 2 higher flowing Cats. I removed the resinator from my old exhaust. And it resinated like crazy. It was stock except for a flowmaster muffler. Like I said the largest restriction in our exhaust is every thing from the Y-cat forward. For altimate flow look at what I've got. If your not boosting your car however, it will be too much flow. That is something that you also need to watch out for. If your exhaust flows too well, you'll reduce your back pressure to the point that you'll start losing torque.

By keeping the resinator and running a single in dual out turbo muffler you will maintain a fair amount of back pressure, but still flow much better then stock because of what you've done with the Cats and still keep the volume fairly quiet. This will probubly still be a little louder than stock.

SomethingElse · #6 11-21-2006, 11:27 AM

DO A SEARCH!!!!

dont use flowmaster.

mikecg · #7 11-21-2006, 11:48 AM

Quote:

Originally Posted by SomethingElse

DO A SEARCH!!!!

dont use flowmaster.

There's nothing wrong with Flowmaster. Thats what I have always used. They dont sound as raspy as the Magnaflow. However the Magnaflow does flow alot better. But reguardless he wont want either of those options because they both tend to be quite a bit louder. I accually tried replacing my flowmaster with a magnaflow to stop the resination, but it accually made it worse.

benebob · #8 11-21-2006, 11:56 AM

Real men use dynomax race mufflers.

WHAT WAS THAT? SPEAK UP I CAN'T HEAR YOU!

SVXtacy · #9 11-21-2006, 11:57 AM

My Remus came in today. I'm going to try it out with nothing, and add cats and whatnot if it gets too ricey/loud. Had it set up on my old VR-4 that way, and it was so deep that I didn't have to put on cats or resonators for sound muffling. Hope it turns out the same on this thing. I'll let you know how it turns out as an exhaust option. Seems like no one really gave them a chance, so I thought I'd give it a shot so we all know if it's a good choice or not.

SVXMAN2001 · #10 11-21-2006, 11:58 AM

would it be a bad idea to just replace the the Y forward as you suggested? And keep the remaining stock? This car is going to be kept stock (engine wise), so i just want to upgrade a little bit without sacrificing sound. Do you think i would have resinating issues?

Another question...now if I go to 2.25 from the exhaust manifold how does that work? The stock piping is obviously smaller, i am just wondering how they mate up the larger piping to the stock exhaust manifold.

mikecg · #11 11-21-2006, 12:12 PM

It is a littlw tricky. The exhaust guy that did mine had to grind down one side of a round exhaust gasket. You could also ask a poticular member of a certain SVX Network if he would be willing to make you a set of headers.

Headers + 2.25in pipe + Highflow Cats = Great flow.

SomethingElse · #12 11-21-2006, 08:02 PM

Quote:

Originally Posted by mikecg

There's nothing wrong with Flowmaster. Thats what I have always used. They dont sound as raspy as the Magnaflow. However the Magnaflow does flow alot better. But reguardless he wont want either of those options because they both tend to be quite a bit louder. I accually tried replacing my flowmaster with a magnaflow to stop the resination, but it accually made it worse.

I guess im partial to the magnaflow. I hated my flowmaster on my svx especially when the it was cold. But i love them on my monte carlo SS. I kept the stock pre cats, and put in aftermarket 2ndary cat, then cherry bomb to magnaflow on my wifes car. she doesnt like loud cars either.

My car has all high flow aftermarket pre cats 2 inch, 2 into one cat, then small resonator to magnaflow. its somewhat louder than hers.

SVXMAN your not to far away you can come down and here what mine and hers sounds like.

SVXMAN2001 · #13 11-22-2006, 06:42 AM

sounds good, once i get around to bringing that car down for ya!!

elninoalex · #14 11-22-2006, 10:16 AM

If you don't want to appreciably increase the exhaust sound, you'd probably be best served by leaving it stock. Tinkering with it in just about any way will increase sound more than flow. I built many exhaust systems for my last two SVXs and my new SVX is going to keep the stock system. If you're not boosting or squeezing, there's not enough 'flow' to be found to make it worthwhile if sound is important to you. What is a 'high-flow' cat anyway? Marketing? My factory cat had 207K on it with rusted flanges coming in. I put a 'high flow' cat on there(just because I had to replace it anyway) and got no noticable increase in power. Not that I expected any. I've seen enough of them tested and panned by the car mags flowing even less than stock. But if you must tinker, here is a system to consider: Leave everything stock back to and including the center cat. Put a 'Y' pipe (2.5" in/dual 2" out) after the cat(or the resonator) and run 2" pipe to two separate Dynomax Turbo Mufflers. That will keep it mellow-sounding and will increase flow. I don't know if you'd notice the difference though without pushing an extra 100hp through it. But whatever you do, have fun!

Stephen

oab_au · #15 11-22-2006, 02:53 PM

Quote:

Originally Posted by elninoalex

If you don't want to appreciably increase the exhaust sound, you'd probably be best served by leaving it stock. Tinkering with it in just about any way will increase sound more than flow. I built many exhaust systems for my last two SVXs and my new SVX is going to keep the stock system. If you're not boosting or squeezing, there's not enough 'flow' to be found to make it worthwhile if sound is important to you. What is a 'high-flow' cat anyway? Marketing? My factory cat had 207K on it with rusted flanges coming in. I put a 'high flow' cat on there(just because I had to replace it anyway) and got no noticable increase in power. Not that I expected any. I've seen enough of them tested and panned by the car mags flowing even less than stock. But if you must tinker, here is a system to consider: Leave everything stock back to and including the center cat. Put a 'Y' pipe (2.5" in/dual 2" out) after the cat(or the resonator) and run 2" pipe to two separate Dynomax Turbo Mufflers. That will keep it mellow-sounding and will increase flow. I don't know if you'd notice the difference though without pushing an extra 100hp through it. But whatever you do, have fun!

Stephen

This is the best bit of info, for people that want to experiment with their exhaust. Its not a slow reving V8, so it will never sound like one.

Leave everything stock back to and including the center cat.

Harvey.