Anyone ever think about this? (Cat-back exaust)

[00GTZ00]

*Disclamer* these thoughts will apply to people that do not have $500 to spend on a cat back and are only looking to add "Basic" mods to their car. If you are going all out, plan on using FI or Nitrous you will benifit from the 2.5"+ Cat-back systems.and generally should not bother trying to mod your exaust with the following thoughts because you will be changing out all the piping to a bigger size. But I guess you could use this mod untill you have the money to add a full cat back and FI. in the end it is allways up to you!

First off does everyone agrees that just getting a muffler four our cars will
yield about the same power as the cat backs right?

Well After looking at some of the catbacks for the eclipse, I found that some of them still use the 2.25" dia tubing. So what about this idea?

If the stock tubing is 2.25" and the "cat back" is 2.25" Why don't we just replace the bends of the exaust with some manderal bent parts? Now stick with me here. Everyone is always talking about the "tuning" aspect of a cat back. Well what other than the bends in the exaust would change from the sock system? NOTHING! The bends in the exaust, if they are manderal bent, would be the ONLY advantage of a $450 cat back than the stock system. We have a "Tunnel" under our cars that the exaust runs through, And so does the eclipse, so the exaust can only be routed one way to the rear of the car.

So if the Exaust LENGTH is allways going to be the same on our cars, and all the BENDS in the exaust are going to be same, How will one company's cat back change from the other? By the muffler. The flow properties of the muffler that you buy will be the ultimate decision on how much power the exaust makes. Right?

Now The only advantage that I can see the 2.5" piping having over the 2.25" piping is if you are using some type of FI. Then and only then would you really see a difference in HP by using 2.5 over 2.25. or hell you might even want to think about using 3" pipe if you are really pushing some HP. So if you have FI then just replacing the stock bends with manderal bends would help a little but not as much as bigger piping would. This would be a reason to spend $450 on a cat-back that is at least 2.5" in pipe dia.


So the way that I see it, the only way to improve on the Stock system is (if you are not using FI):

1. Replacing the "stock" bends with manderal bent parts
2. Replacing the stock muffler with the one of your choice

I think that this would be a MUCH cheaper alternative for 80% of the people on this board (everyone not using FI)

[pinoyesv6]

So the way that I see it, the only way to improve on the Stock system is (if you are not using FI):

1. Replacing the "stock" bends with manderal bent parts
2. Replacing the stock muffler with the one of your choice

I think that this would be a MUCH cheaper alternative for 80% of the people on this board (everyone not using FI)

if you are gonna replace the stock bends, you might as well replace the whole thing. i mean probably you'd take out the stock resonators. and then if you cut out all the stock bends and weld on some "better" bends in the end, will it be better?

i know with some companies like borla for example, have awesome warranties with their exhaust. a million miles is alot. yea it might cost alot in the beginning but think of this. you hack up your stock exhaust. you put nicer bends lets say. maybe add a pipe here and there. and bam, your exhaust is filled with welds everywhere. we all know that your exhaust is the weakest at the weld. so lets say after a few years, your exhaust turns into rust, and you get things redone. thats another cost. comparing to maybe like a store bought cat back where its like one big piece of pipe thats bent. maybe it will come in several pieces but its a buncha big pieces taht have flanges on the end so you can just bolt it together.

so yea, you're right about having a minimal gain with a store bought system but looking at the big picture. things now and later, maybe a store bought cat back isn't a bad thing.

[Reelax]

optimal piping size for NA i4 is 2.25"... but optimal size for NA v6 is 2.5".

i am running 2.75" on my v6 (same size as my downpipe) but will have to go to full 3.0" when my car goes FI and replace my downpipe as well. btw, i have no cats and that made a HUGE difference.

[00GTZ00]

Pinoyesv6 - Those are some good points. and as far as the resonaters they would stay stock on the car, as many aftermrket catbacks generally will come with them (for example Greddy, Tunabe and "TRD" all have resonaters to replace the stock ones). But say that your exaust welds rust after 3 years and you get a small leak in the weld. How much would it cost to fix? Well here in houston you can go to a company called southwestern muffler on Hwy 6 and lastime I had exaust work done with them they gave a warantee on their welds for the life of the car. So if you could find a shop that offers this you would never have extra cost to reweld the bends.

But even if you had to pay to get them rewelded after 3yrs what is the cost? $10.00 $5.00 $15.00? and how many years would it take to equal the cost of the cat back?

Well lets say tha tyou have to buy 4 45deg bends and 2 90 degree bends to replace all the bends in your exaust. Lets buy then from RRE:

4 45deg 18 gauge 2.25" bends will cost $60
2 90 deg 18 gauge 2.25" bends will cost $30
Shipping ~15.00 3 day ground fedex (this is based off spings that I shipped 3 day for $11.00)

So for ~$101.00 you could buy all bends to replace the stock ones.

and lets just say an even $110.00 for the muffler and tip (all depending on the muffler that you get, prices here will vary from $80-$200)

So now we have spent $212.00

Now for the install. Lets say that the install runs you $100.00

So now we are at $312 for everything. I think that this is an average price for everything.

Now lets look at Cat back prices for the eclipse:

APC: $493.25
Borla: $629.99
Greddy: $500.00
HKS Axel Back: $380.00
Tunabe: $550.00
TRD: 525.00

And lets go ahead and leave out the cost for install and average the cost for these cat-backs: AVG= $513.04

so the avg cost of the cat back minus the cost of the "replacement bends" is:

$513.04 - $312.00 = $201.04

A differance of $201.04

And if it cost $20 every three years to fix rusted welds It would take 10 trips back to the welding shop ( or 30 yrs ) to equal the cost of buying a pre-made catback and have it modified to fit our cars. this is assuming that the shop charged $20 everytime that you went back for a fix.

So now, in my mind, the question would be is it worth your time to go get welding work done every three yrs?

[pinoyesv6]

let me start off by saying i totally agree with you on this. im just looking at other options and things to look at. i know an exhaust shop here that will replace all the piping and build you a mandrel bent cat back for 120. you just have to supply the muffler. its made up of cut up pipe though. so yea. so i feel you on the price difference. some mufflers like the borla can cost near 200 or more dollars and some mufflers like the greddy can only be found on a cat back, tehy arent universal. so thats something to think aobut.

also, some exhaust are CARB and 50 state legal. so depending on where you live you won't get in trouble with a stoer bought exhaust opposed to a uni muff and some custom pipe. i mean u might still get in trouble but it will be easy to fight your case with the paperwork that comes with the exhaust.

so about the time. hmm. minimum wage is a lil more than 5 dollars an hour. say you spend about 2 hours at the exhaust shop to get it fixed and to wait in line. so thats more than 10 dollars lost per trip. 20 dollars per trip to get the things fixed. thats 30 dollars total. but then lets say you're making 40-50 dollars an hour, then like yea you're just being cheap lol.

resale is another issue. i mean its easier to go back to stock with a store bought cat back opposed to a custom one. and it will be easier to sell a greddy catback than some universal muffler and some custom pipe work that the guy down the street did. i know some people lease their cars or get a new car every few years so this is something to think about.

[00GTZ00]

so about the time. hmm. minimum wage is a lil more than 5 dollars an hour. say you spend about 2 hours at the exhaust shop to get it fixed and to wait in line. so thats more than 10 dollars lost per trip. 20 dollars per trip to get the things fixed. thats 30 dollars total. but then lets say you're making 40-50 dollars an hour, then like yea you're just being cheap lol.

so you are factoring in the "my time is money" thoughts? or is this what you are saying that the person doing the repair gets paied?

Because if it is the "my time is money" senerio then I personally would not count this in the equation because working on my car is a hobby. It is on my FREE time to do what I want. I work 8-5 and at night on my business. I do not make any money working on my car, hell if anything they are just money pits, LOL.

And the guy/gal working on my car fopr the welding get payed more thatn $30 an hour at the muffler shop I am in the wrong business. Around me they average $20-25 an hour for welding labor. And it should not take more that 30 min to repair welds on the exaust. so your talking about $10-$12 that the shop has to payout for the 30 min of labor then add in there overhead, I think that $20 is a good estimate for 1 person at a welding shop to work for 30 min.

resale is another issue. i mean its easier to go back to stock with a store bought cat back opposed to a custom one. and it will be easier to sell a greddy catback than some universal muffler and some custom pipe work that the guy down the street did. i know some people lease their cars or get a new car every few years so this is something to think about.

Yes I do agree 100% that retail is another issue. It would be better to by a full after market exaust so that you can easily replace it when you sell the car. But couldn't you do the same if you just bought a stock axel-back? just put the stock axel back back on the car if you are to sell it? and yes of course you could sell a store bought cat back better than the "home" version. I don't even see it feesable to sell the "home" version cat-back.

[pinoyesv6]

so you are factoring in the "my time is money" thoughts? or is this what you are saying that the person doing the repair gets paied?

Because if it is the "my time is money" senerio then I personally would not count this in the equation because working on my car is a hobby. It is on my FREE time to do what I want. I work 8-5 and at night on my business. I do not make any money working on my car, hell if anything they are just money pits, LOL.

And the guy/gal working on my car fopr the welding get payed more thatn $30 an hour at the muffler shop I am in the wrong business. Around me they average $20-25 an hour for welding labor. And it should not take more that 30 min to repair welds on the exaust. so your talking about $10-$12 that the shop has to payout for the 30 min of labor then add in there overhead, I think that $20 is a good estimate for 1 person at a welding shop to work for 30 min.

im factoring the my time is money thing. i mean yea its your hobby but if you're taking off from work to like get your exhaust fix cuz of a ticket you might have from a leaking exhaust then yea.

[00GTZ00]

ok, I see.

exaust shops are open on the weekends here in houston. I do not know about the rest of the country though.

and if some one is getting payed the 40-50 an hour like you mentioned then most likely they are going to be on a salary. Which in turn means that they can take the time off without a hit in pay. at the wost case, If your boss is a complete dick you would have to take a 1/2 day vacation. But everywere that I have worked, they have never cared to much if I took off 2-3 hours early to go fix a ticket, get my car inspected, Run to the bank etc. etc. as long as I do not do it every day no one says a ting about it. No that is just my own personal experiances, everyone is different.

But lets say that "my time is money" + cost to repair welds = $50.00 every time it will still take 12 yrs to finally equal the cost of the pre-made cat back.

[Auto-9]

Here's something to think about. We dynoed a V6 Eclipse sportronic with both a mandrel bent axle-back and a press bent axle-back, using the same muffler. The mandrel bent exhaust yielded 3.2 whp 3.9 wtq over stock, and the press bent exhaust yielded 3.1 whp 4.1 wtq over stock. Granted this isn't a cat-back, but it should give you something to ponder, especially since we know roughly half or more of the bends are from the axle on back.