3'' DP & 2.5'' exhaust... What 2 do..

[Turbo6Smackdown]

Ok, what do I do? I'm orderin' up a 3'' DP, and a dual 2.5'' exhaust. With dump and electric cutout... What do I order the cutout to match, the DP or the exhaust? What have you guys done?

 

[Spooled231]

You will need to order the downpipe with a test pipe cutout. This will replace the CAT itself. The electric cutout will take the place of the cap on the test pipe cutout.

John Martin
1986 Buick T-type
9.71 @ 140

 

[TR Custom Parts]

3" downpipe = 3" cutout.

 

[Turbo6Smackdown]

You will need to order the downpipe with a test pipe cutout. This will replace the CAT itself. The electric cutout will take the place of the cap on the test pipe cutout.

John Martin
1986 Buick T-type
9.71 @ 140

No ****... lol.
My question was... What size do I order the cutout at. Somewhere, there's going to be a stepdown, from 3'' to 2.5''. Do I want that step from the DP, to the dump, or from the dump to the exhaust tubing....

 

[DR BOOST]

the cutout is matched in diameter to the downpipe.

the electric cutout bolts to the 3 bolt cutout flange on your exhaust.


in case this makes no sense...just order a 3" electric cutout

 

[ANDYS87]

Just buy a 3inch test pipe with dump opening. The 3 inch test pipe fits onto your 3 inch downpipe. The other end is a flange that matches up to the flange welded onto the Y-pipe(doesnt matter if it is a 2.5inch y-pipe...the flange is the same). Maybe someone can post pics. Hope this clears it up for you

 

[christians87]

test pipe

Where is the best place to get a test pipe with dump for a good deal? I just got in my new 2.5 in pypes system and i need that flange thats on the end of the pipe.

 

[ANDYS87]

Try the vendors on here...gbodyparts, RJC Racing, etc...............

If you can't find it, you can look on ebay

 

[gczarny]

Ok, what do I do? I'm orderin' up a 3'' DP, and a dual 2.5'' exhaust. With dump and electric cutout... What do I order the cutout to match, the DP or the exhaust? What have you guys done?

what we have done is to run good 3" DP and 2.5" duals to the 9's , with your mods the only thing you will noticed is more noise , V6 is just noise in my opinion with open pipes , spend money somewhere else I'm suggesting unless you like it like that :redface: ,then do it at DP

 

[viper04]

Test pipe

what we have done is to run good 3" DP and 2.5" duals to the 9's , with your mods the only thing you will noticed is more noise , V6 is just noise in my opinion with open pipes , spend money somewhere else I'm suggesting unless you like it like that :redface: ,then do it at DP

I was just wondering are you saying test pipe with cut-out don't work. Thanks.

 

[gczarny]

I was just wondering are you saying test pipe with cut-out don't work. Thanks.

it's like putting K&N filter on stock car and claiming 15HP gain ! sure if you finaly replaced your clogged up stock filter after two years , what I mean is what I said , unless you enjoy that V6 noise what you will pay for electric cutout will buy you a lot of things that will outperforme gain from open exaust ,he said he is buying 3"DP and dual 2.5" right , that's all you need to go much faster then 009's will ever take you to, that's all :wink:

 

[Turbo6Smackdown]

the cutout is matched in diameter to the downpipe.

the electric cutout bolts to the 3 bolt cutout flange on your exhaust.


in case this makes no sense...just order a 3" electric cutout

No, it's not machined to the diameter of the DP. Because I'm buying it separately It'll be formed to whatever diameter I want. I KNOW a cutout is going to be the diameter of the exhaust, or the DP...that much is obvious.. lol. (what am I lacking in my questions? someone help me)
I know where an electric cut out bolts to.... ugh....
And there's more to be gained by a cutout, than just top end... I know there's alot of people that will have evidence to the contrary, but, quick spoolup is my main concern. I dont race on tracks or highways. Spoolup is my number one priority. I'm not sure I'm convincable to the ''an open dump will do nothing for your spoolup'' mindset....
My question is, there's going to be a little forming of ONE of the tubes... somewhere. Do I step it down/up at the DP/cutout joint, or the cutout/exhaust joint...

At any rate, I think I'm beating my head against a tree here. lol. thanks. Mods, please delete this thread... I'm going nowhere fast.... I don't know how to explain myself lol. sorry.

 

[Powder]

All your questions will be answered by simply looking at a test pipe assembly and then comparing it to the cat I assume is currently on your car. No stepdown will be needed.
MH

 

[conn84gn]

When you order your DP order the Test Pipe too (With or without Cutout)
Slips on the Down pipe and
It will bolt right up to you 2.5" Exhaust flange.

 

[salvageV6]

If you order up a 2.5" dual from a typical Buick vendor they will put the GM flange on the end that goes to the cat side, even if you are deleting the cat. with a test pipe most systems have the GM flange, even the 3" dual systems since the test pipes and cat.s. have that flange also.

If you are building a custom exhaust they should weld a GM flange on it, that I assume would be readily available to them, and a standard 3" cat. replacing test pipe with cutout will work with your 3" downpipe and custom exhaust.

Remember the cat. hanger which bolts to that flange, is a main tie point to hold the exhaust up also.

And you won't gain a thing with more noise.

If I misunderstood you also, then............ nevermind....

 

[Turbo6Smackdown]

if you have a 2.5'' diameter tube, with the gm flange on it, and a 3'' tube, with a flange on it, and you bolt that together, what do you think is going to happen... There's going to be a pretty decent sized 'shelf' in there, due to the different sized pipes...................................... I can see now, that I'm going to have to do the research on my own lol...........

 

[salvageV6]

The flange is thick with "about" a 4" x 6" hole in it and the tubes are welded in the back of it like a collector, there should be (2) 2.5" tubes back into it if it's a true 2.5" dual exhaust.

Same with the test pipe a thick flange with a 3" pipe down the center from the test pipe (with or without a cutout) or cat hole.

They mate up just fine.

Your "research" should be looking at a few I agree.

No shelf no big step and no big restriction, unless you are going to a single 2.5" tube that would suck.

I'd buy a proven exhaust in stainless from a reputable vendor that knows Buicks.

 

[salvageV6]

The Hooker 2.5" exhaust in your signature should have that proper setup.

I'd go look at that one.

No need to change that out unless it's rotted, in that case just get a stainless replacement.

A single 3" downpipe easily mates with a dual 2.5" pipe system at the flanges in the stock location using the stock hanger.

Length of test pipe is a great concern however, it is usually determined by the length of the 3" downpipe and how far under the car it comes, many vary by up to 5" even.

Test pipe that connects between the downpipe to the GM exhaust system flange must be sized in length properly for the system.

The exhaust system flange should be in one place on all systems where the stock hanger holds it in place.

Normally when ordering all 3 items the downpipe, test pipe with cutout, and exhaust system from one vendor all the parts will match.

Cutout sized in 3" should work off the 3" test pipe which is sized to the downpipe for a slip fit.

 

[Turbo6Smackdown]

I'm only running a cut out. NO TESTPIPES. I'm obviously changing my hooker.... because it's rotted... lol.
I'm ordering the stainless from pypes, the cutout with electric dump from bandlanz, and the DP from gbodyparts. I STILL want to know, how my cut out is going to fit my exhaust, if it's 3 inches, to match the downpipe. There will be no flanges in my set up.
Is there step down pieces I can purchase? LIke sort of a funnled piece of exhaust tubing, that'll bridge the gap between my tubes?

 

[TR Custom Parts]

I think you have lost us! You got a downpipe that is 3", then you need a 3" DUMP pipe to connect to your DOWN pipe. The DUMP pipe connects to your exhaust system. The electric exhaust cutout bolts on to the flange that comes off the DUMP pipe so you need a 3" electric exhaust cutout. End of story!