Downpipe & Exhaust - time to upgade

C

cdub

I Want to Go Fast
Joined
Mar 4, 2004
The time has come, well it came a long time ago but I am just now getting to it, to upgrade my DP & exhaust. I was planning to go with a 3.5" THDP and a SS 3" duel exhaust with magnaflow stainless straight through mufflers. It seems the THDP's are hard to come by these days, any idea of they are still available new?

Any other input would be greatly appreciated, anyone happen to have a sound clip of this exhaust setup?

I am running a GT 6131 turbo, what is the biggest DP I can use with that?

Anyone using the RJC downpipes? Looking for some input on these.

May also want to get a DP with a track/test cut out, I know someone used to make a nice one with an electronic switch for the cut out, anyone know if this is still available?
 
After speaking with Jack Cotton I'm leaning towards the following setup:

Cottons 3" dual aluminized steel exhaust system with Magnaflow SS straight through mufflers.
Cottens 3" aluminized steel DP with Turbonetic's Evoloution 38mm external wastegate
Variable Boost Controller

Any thoughts on this, anyone already running it? Any sound clips of it would be great if possible.
 
Most definately the best exhaust upgrade I made other than the THDP was the electric cutout. I've ran my STOCK intermediate pipe and STOCK muffler with the THDP to 12.70's @ 109 mph with the exhaust closed:eek: and then 12.11 @ 113 mph with only a flick of the switch. No climbing under the car with a glove to undo the hot asZ exhaust between runs, don't have to wear grease monkey clothes to the track anymore, keeps the interior clean too. Great for sneaking one on a un-suspecting stop light race. Red light/quiet, Green light/gone...

http://www.buickgn.com/electricexhaustcutout.htm

DMHONEmedium.jpg


electricCutout.jpg
 
After discussing things with Jack Cotton, he explained to me that I'm actually better off running through the exhaust. Apparently the modern exhaust systems flow so much better than the old ones, you can lose power going to a dump.
 
Not a big fan of 3" exhaust systems, but I would take Jack Cotton's advice over mine any day.
 
I have a 3"THDP and an ATR single shot 3"....it's a little loud at times, but my car isn't a daily driver!! Plus a sleeper with single exhaust(if ya aren't running funny gas)
 
Loud inst an issue, in fact I prefer it. It is not a daily driver.

My main issue is that the 2.5" dual system is Stainless and 3.0" dual is aluminized steel. Any issues with the aluminized? I know it will rust, but this car dosn't see the rain unless it's a freak storm, never sees the snow.
 
2-bit opinion mostly. Not crazy about the sound, and I think at some point the concept of diminishing returns would apply. (while this may be a bit of apples and oranges, the following is true: my ex husband, recently went from a 2 1/2 to a 3" on his monte carlo and slowed down. I still have the time slips to prove it! something about not just beating your ex, but humiliating him,:D he was a dumbas anyway, but that's not the point) Bottom line is 3" systems were unheard of when I started tearing into my first TR and I've stuck with what's always worked for me.
 
The reason I went with all stainless 3" is because it should last "forever" and 3" out of the turbo and all the way out, so no need for dual. I have a Pitbull ATR muffler with no cat.converter. The impeller on the turbo provides minimal back pressure.
 
Exhaust

I think your on the right track with the setup from cottons....But whatever you change or decide to do make sure you spend a little extra and get the external wastegate downpipe. With the extras you have already you dont want to have to deal with boost creep later on or should I say if you do get boost creep it will be easier to fix with external wastegate......That downpipe from gn1 performance on ebay seems like an awsome deal and thats what Im getting when I upgrade....HTH Tim
 
86BLACKT said:
The reason I went with all stainless 3" is because it should last "forever" and 3" out of the turbo and all the way out, so no need for dual. I have a Pitbull ATR muffler with no cat.converter. The impeller on the turbo provides minimal back pressure.
Click to expand...

Ya i would prefer do go 3" dual SS, but the guy who bends the SS pipes for Jack dosn't have a 3" mandrel bender, so it's either 2.5 SS or 3.0 aluminized. I just like the look of dual exhaust better than single, so I'm gonna stick with that.

Sixstringterror said:
I think your on the right track with the setup from cottons....But whatever you change or decide to do make sure you spend a little extra and get the external wastegate downpipe. With the extras you have already you dont want to have to deal with boost creep later on or should I say if you do get boost creep it will be easier to fix with external wastegate......That downpipe from gn1 performance on ebay seems like an awsome deal and thats what Im getting when I upgrade....HTH Tim
Click to expand...

For sure, going to stick with the 38mm external wastegate and a boost controller. No doubt on that.

Ya the GN1 DP & 38mm external wastegate is a good deal, $529 w/ shipping. I'm paying $558 for cotton's dp and 38mm external wastegate, but he is less 100 miles from my house so I will be driving out there to get everything installed there, and I also save a little on shipping.

Once I get a few more miles on the old girl, only have 650 on the new motor would like to get 2k on it before hitting it with alky, I have an alkycontol system sitting on my garage work bench just waiting to go it.. should probably make sure I get the 275/60/15 MT ET Streets mounted up before I take her out with all the new HP's I will be making.... wider wheels should be in within a week.
 
Just talked to Jack and I'm bringing in my GN tomorrow morning to get the 3" DP with the 38mm external wastegate, I'm still on the fence on whether to get the 3" dual aluminized steel or 2.5" dual SS exhaust...

guess I have till 9:00 AM tomorrow to make up my mind...
 
I'd go with the 2.5" stainless.....better/easier fit under the car, and you don't have to worry about the pipes rusting. They usually rust from the inside out due to moisture from combustion....so even if your car never sees rain or snow, the aluminized will still rust.
 
I'd go 2-1/2 SS also. I've got the Tial 38mm gate which came from Jack and it's really a nice piece. Fit right in place of my POS old ATR external gate.
 
Decided to go with the 2.5" SS duel exhaust setup, ended up doing a bit of custom work, welded on 18" of 3.5" polished stainless tips. Looks fantastic, sounds great, hauls major @ss! Also went with the Racegate 44mm external wastegate, couldn't find a 38mm DP, so oh well, had to upgrade :D

I would also like to thank Jack and his son "Bobo" for letting me hang out a the shop with them all day while they worked on my exhaust, and for doing such an excellent job, top notch all the way. Pics coming.
 
cdub said:
After discussing things with Jack Cotton, he explained to me that I'm actually better off running through the exhaust. Apparently the modern exhaust systems flow so much better than the old ones, you can lose power going to a dump.
Click to expand...

I agree with that. My car runs like crap with the dump open.
 
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