Just went to get my exhaust done. Need help...

derekhay316

Registered User
Just went to a local muffler shop to get my exhaust done and they said they couldn't do custom downtubes because there were o2 sensors and what not. What should I do? They gave me a quote of $400 canadian to replace the passenger side cat, cut off mufflers and install a resonator? What should I do? I'd really like to go downtubes, resonator and then no mufflers. What should I get them to order me for the cat? and does anyone have a magnaflow resonator part number for me? Thanks. I have an 89 SC.
 
(shameless plug mode on/)

If ya wanna go racin'...2-1/4" downtubes

(/shameless plug mode off)

:)

'bird


8993pipes1466.jpg
 
You have a few options here. You could check out a few other exhaust shops. Bring pics with you of other car's exhaust to explain exactly how you want your's done. You could also buy a pair of downtubes from tbird88, and then you could go with or without cats (depending on your local emissions regulations). If you need cats, you can just have the exhaust shop cut the downtubes and install the cats.

Here are pics of my exhaust. I used Catco 12" long high flow cats from Summit, a Magnaflow 18" long resonator (#12278), and no mufflers. It has 2.25" downtubes, 3" single after the resonator into dual 2.75".



Exhaust1.jpg
Exhaust2.jpg
Exhaust3.jpg
Exhaust4.jpg



-Rod
 
Unless you ported your 1 7/8 manifolds I personaly don't think 2 1/4 down tubes will do you any good. Also, find another shop to do your work, never heard of someone saying they can't do exhaust because of the o2 sensor! The magnaflow part numbers are
12578- 3 in 2.25 out
12588- 3 in 2.5 out
Go with Jegs around $100 with shipping USD
 
Yes, I forgot to mention that I have ported manifolds on my car.

Those Magnaflow part numbers are for single in/single out mufflers. Dual 2.25" in/single 3" out is 12278, dual 2.5" in/single 3" out is 12288. See for yourself here at Magnaflow's website

-Rod
 
Ok well which one should I go for. I have totally stock 89 SC Exhaust. Jake you said :
12578- 3 in 2.25 out
12588- 3 in 2.5 out

Well I looked on the magnaflow website and the 12578 is an offset 3" and the 12588 is a 22" long with 3" and 2.5" piping. Would that fit on my stock exhaust???

And racecougar, would the 12278 or 12288 be the best bet for me? Those are 18" long. Which would fit better on my setup? I don't think i'll be changing much of the stock piping. Thanks.
 
I would start the planing, building of your exhaust at the header & work back.
And the 2 1/4 pipes are a plus,even if you have stock headers.

I would start with the 2 1/4 then go back.

2 1/4 was the biggest bang for the buck on my sc exhaust mod.

I have a stock inturnal motor 250 plus RWHP.With stock headers.

JAKE what is your RWHP.
 
derekhay316 said:
And racecougar, would the 12278 or 12288 be the best bet for me? Those are 18" long. Which would fit better on my setup? I don't think i'll be changing much of the stock piping. Thanks.

The only difference between the 12278 and 12288 is the diameter of the dual pipes going into the resonator. I'd personally use 2.25" downtubes into the 12278, which is what I used. Take a look at the pics I posted. That's the 12278, with 12" long cats in front of it. Plenty of room.

As I stated before, the part numbers that Jake posted are for rear mufflers, not to be used as a resonator. Those are only single in/single out, where as the two part numbers I posted are dual in/single out.

-Rod
 
I don't know exactly what my rwhp is but my best 1/4 time is 14.722 in 60 degree weather. With VERY few mods 3:73:1 gears, home made intake system, BFG drag radials, and exhaust work. 2 inch from nonported manifolds, into 2.5 into a y pipe 3 inch in 2.5 out to 40 series flowmasters. When I posted that I didn't know of the ported manifolds, YES 2 1/4 inch down tubes will be better on ported manifolds, but not stock manifolds. Does your blind neighbor know you up-graded your exhaust on your 250+ BONE STOCK car?
 
Sorry about wrong info.

I really try not to do that,just goes to show you always do you're own research before taking someone's word. Got my 2's and 5's messed up.
 
Jake the last ET was14.686,stock size tires.stock headers,with 2 1/4 down tubes with cats
the RWHP at that run was 221.0. And the 60' was 2.041.

derekhay316 THERE IS NO IFs OR BUTs about it,the 2 1/4 are the way to go.
Listen to racecougar he will streer you right.

I am out of here
 
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WOW!!!!

Randy, you must have the fastest stock sc on the planet or maybe you're quarter mile is a little shorter than the rest of ours. I've never heard of a stock sc doing better than a 15.1 in the quarter but you learn something new everyday. Are you using a g-tech probe to get your horsepower reading? When I go to the track my time slip doesn't give hp. And yes racecougar 2 1/4 is the way to go with ported manifolds.
 
Jake , I dont think my wife Connie is the fastest stock SC.that day was
the first time she had drag raced in a car.She used to pilot a pro-stock
Harley Davison with some 150M.P.H. passes though.

And its not a stock SC ,but the motor is stock.

Are H.P. reading comes from STIEGMEIER dyno in St CHARELS,MO.
And tuned by BRIAN HERRON OF APTEN. www.bjherron@apten-us.com

Brian tunes a lot of the fastest SC but I dont know that connie would be one
of those.If I jump in it I am sure it would be a little faster.

I think she posted one of her time slips in the race track results part of this board.

derkhay316 ,If you go with the t-bird88 pipes they will give you room for mod
later,like porting out the headers,and you head gaskets will like you better.
 
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Ok you guys are saying go with the 2 1/4". Does my sc come stock with 2" piping or 2 1/4"??? I just want to leave it with the stock piping.
 
Originally posted by derekhay316
Ok you guys are saying go with the 2 1/4". Does my sc come stock with 2" piping or 2 1/4"??? I just want to leave it with the stock piping.
Stock exhaust pipes are 1-7/8".

'bird
 
derekhay316, You can go to www.supercoupeperformance.com/exsys.htm

There are some more pictures to look at this may help you decide what you want.
I beleive the parts are over priced,but there aren't not many choices for the sc.
exhaust (store bought)

1. down tube purchase
The biggest restrictions in are exhaust are the down tubes.You need to buy or make
the down tubes with a bung welded in (if i remember right) in the passenger side.
The bung is for screwing in the 02 sensor.(you have to have this for the sc to run right)
The other 02 sensor screws into the stock header on the driver side.

2,cat purchase if you want or need them.
The next part that is a restriction is the cats.If the law makes you have them where you live.
you will need new cat to fit you new down tubes.If you dont need them,or dont want cats.
you can use the down tubes from tbird 88 his seems to be the cheapest.

3,resonator
is the next restriction race couger gave you some part numbers and places to buy
Just make sure that the inlet holes will fit your down tubes,or cats that you choose.


If I understand you right the muffler shop that you went to did not have,or want to
make the down tubes with the bung in one of the down tubes for one of the 02 sensors.
The other 02 go's in the header.So if I understand you right.You just need to buy down
tubes,and take them back to your shop and they can do the rest.

I hope this will be of help to you. I am sorry about if it seemed that your thread got hyjacked this morning.
Or off the subject.

THANKS RANDY
 
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