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Discussion Starter #1
ok i have the big bad 2.5 in exaust from Saab. I want to get 3" downpipe and a race cat. Two questions should i go 3" all the way and if i just keep the 2.5 and add three in DP and a new cat will i hear a diff because i really like my car as it sounds.

also i am gettin the intake from genuine sabb for christmas.

do i need anyhting else to put the 3 in and cat onto the 2.5

srry bout the scatter brained post long day
 

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I would go 3" all the way personally. And I see you live in Arizona, so I would HIGHLY reccomend water injection. In that climate it would make a serious difference in power, possibly more than the exhaust. (though without the quicker spool up) Turbo cars always run much better with lots of humidity which you probably have almost zero of in Arizona.

Here's a good custom water injection setup for about $250: Eric's Water Injection setup

Cheers,
Dubbya
 

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I have the Saab sport cat-back exhaust on my 1999 9-3 as well. It does sound quite good. I later added a stainless steel 3" downpipe and race cat from BSR and the sound changed just a bit but still sound very nice. Most of the other guys at a few of our meets here in Europe think my car is one of the better sounding ones. As for the power, the big dp will add about 10 hp probably and the turbo will spool up quicker. Also, unless you are shooting for 350 or more hp, the 2.5" after the cat is plenty big.
 

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Second that - any bigger than 2.5" after the cat would be overkill. The downpipe and cat will make a bigger difference by far than whatever comes after them, anyways.
 

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In my experience, the fitting of a Hirsch 2.75" cat back system and JR filter gave an increase in performance of 10bhp.

The fitting of a 3" downpipe and sportcat gave and increase of around a further 20bhp (when fitted in conjunction with the 2.75" cat-back system

However, those figures were recorded on different rolling roads so I make no claims for specific accuracy. This is my experience.
 

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Discussion Starter #6
I guess my next question would have to be which is the right DP and cat for me. I have 1998 GM900 SE 2.0T and I would probably get it installed at a local exausht shop. thanks for the help.
granger
 

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Discussion Starter #7
also dubbya is the water injection pre or post turbo? and will this effect my emissions testing? also would a new DP, CAT, And Intake effect my emissions testing in the us?
 

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The best place to put the water injection is just after the intercooler. Water injection should not effect emissions as it is not activated at the engine speeds that sniff tests are done at. I don't know about Arizona but in some places, if a aftermarket exhaust part or intake part is installed it may need a CARB EO number. As far as I know though, California may be the only such place. Otherwise, for the actual readings of the sniff test, the dp and cat shouldn't effect it either. If you go the race cat route, it will be smart to drive the car a bit prior to the test to get the cat nice and hot.
 

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I'm not sure what other states require it, most states only check for a catalytic converter, and "sniff" the exhaust. I'm "lucky" enough to be in a state where ANY engine modification between AMM and CAT that isn't CARB approved gets you a $800 ticket. Lucky me! You should be safe in Arizona. For the catalytic converter ... you can get a cheap effective 3' cat for the downpipe here.

Good hunting and good luck.

Dubbya
 

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Originally posted by Adrian W:
[qb]What?  You don't want a sewar pipe connected to YOUR turbo?      [/qb][/b]
3 inch, 3 foot, 3 metres.... I'll do whatever you want. Biggest sewer I've built is 13 foot diameter. Anybody want one as a garage
 

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Discussion Starter #14
ok well is one DP better than another. which would you recomened anbd is there anyhting else need for my exausht sytem or am i pretty much done after this.

and will everything in my exausht be 2.5" or bigger?
thanks,
granger
 

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Unless you're going for a very extreme setup, a 3"JT downpipe and 2.5" exhaust will do. The JT is not stainless, but it's very good value for the price.

Ferrita makes stainless downpipes for Saab, but it comes with a pricetag.
 

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Originally posted by Maarten (900 Hirsch):
[qb]Unless you're going for a very extreme setup, a 3"JT downpipe and 2.5" exhaust will do. The JT is not stainless, but it's very good value for the price.

Ferrita makes stainless downpipes for Saab, but it comes with a pricetag. [/qb][/b]
Erm, my JT 3" downpipe is stainless steel
 

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Didn't know that JT made a stainless version - mine's aluminised steel. Two things: I like using 3" all the way back as the larger diameter has preferable sonic tendencies (deeper/lower tone!) Also, my JT is more than three years old now and shows no sign of rust, even at the flex joint. I'm not sure what version of stainless is used on other downpipes, but I have seen stainless crack/fail from heat cycling - something I've never seen aluminised steel do.
 
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