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Question about which flowmaster merge to use

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Old 04-16-2018, 10:05 PM
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Default Question about which flowmaster merge to use

Car: 02 ss convertible with 1.25 bmr springs/koni shocks
exhaust : 1 3/4 pacesetter headers, some random pipe, 3 bullets.

Question: what is the size of collectors of pace setter 1 3/4 headers and which size flowmaster y merge do I need to connect between pacesetter headers and fbody spec magnaflow catback.

Current exhaust:

Last edited by bad_408_vert; 04-17-2018 at 01:21 AM.
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Old 04-16-2018, 10:18 PM
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Usually a Y is defined by the tube sizes feeding it. If you have 3" pipes from the headers, the inlets of the Y will be 3". The outlet of the Y will be whatever size the catback system is.
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Old 04-17-2018, 01:22 AM
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Thanks, I updated my question.
just trying to figure out what the collectors size is for these particular headers so I know which merge to get.
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Old 04-17-2018, 05:08 AM
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I have Pacesetter 1 3/4" headers and 3" ORY and my FM merge is 3" in and 4" out I believe
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Old 04-17-2018, 02:00 PM
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Originally Posted by HCI2000SS View Post
I have Pacesetter 1 3/4" headers and 3" ORY and my FM merge is 3" in and 4" out I believe
Yeah Im not seeing a 3 in/ 3 out flowmaster merge.
What exhaust do you have after the merge?
im pretty sure the catback aftermarket exhausts on fbodies come on 3. 4 exhaust is used by some high hp cars.

Did you have to use a reducer?
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Old 04-17-2018, 03:21 PM
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Originally Posted by bad_408_vert View Post


Yeah Im not seeing a 3 in/ 3 out flowmaster merge.
What exhaust do you have after the merge?
im pretty sure the catback aftermarket exhausts on fbodies come on 3. 4 exhaust is used by some high hp cars.

Did you have to use a reducer?
After the merge I have a Magnaflow bullet muffler in the I-section which goes into a aftermarket catback. You definitely don't want a 3" out. Either 3.5" or 4" with 4" being a little better. I had a shop weld it in and they used a small reducer of some sort
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Old 04-17-2018, 05:13 PM
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Old 04-18-2018, 08:37 AM
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You will need to buy the 3 inch in 4 inch out merge and also 4 inch to 3 inch reducer and have it welded on to the merge.
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Old 04-18-2018, 05:47 PM
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Originally Posted by bad_408_vert View Post
Car: 02 ss convertible with 1.25” bmr springs/koni shocks
exhaust : 1 3/4” pacesetter headers, some random pipe, 3” bullets.

Question: what is the size of collectors of pace setter 1 3/4” headers and which size flowmaster y merge do I need to connect between pacesetter headers and fbody spec magnaflow catback.

Current exhaust:
Im surprised you got those duals inside the stock tunnel brace

I would be interested in seeing more pics from different angles
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Old 04-19-2018, 08:47 AM
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Originally Posted by 01ssreda4 View Post
Thanks! That magnaflow one looks like great alternate.

Originally Posted by Sube View Post
You will need to buy the 3 inch in 4 inch out merge and also 4 inch to 3 inch reducer and have it welded on to the merge.
Thanks for info. Im lowered and worried the 4 part of pipe may bottom out.
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Old 04-19-2018, 09:08 AM
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Originally Posted by bad_408_vert View Post


Thanks! That magnaflow one looks like great alternate.



Thanks for info. I’m lowered and worried the 4” part of pipe may bottom out.
The 4" pipe will not be a problem if you're lowered, since it won't be the lowest point on your car. Both my ORY and bullet muffler are my lowest points
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Old 04-19-2018, 09:32 AM
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Originally Posted by Full-Force View Post
Im surprised you got those duals inside the stock tunnel brace

I would be interested in seeing more pics from different angles
it took some massaging but it worked with a very tight fit.
The mufflers are 3.5 at that portion.
I ll take more pictures when they come off.
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Old 04-20-2018, 12:43 PM
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My 99TA had the Mufflex / Flowmaster dual 3 inch merge collector to 4 inch out. It had a 4 inch to 3 inch reducer to hook up to the SLP 3 inch Dual/Dual catback. The merge collector never scrapped over 130,000 miles over15 years. My car was lowered about 1 inch with SLP Eibach springs. On nasty speed bumps the I pipe would scrap.
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Old 04-20-2018, 09:06 PM
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👍👍
thanks for info and help guys .
ordered the flowmaster 3 to 4 y merge , super 10 muffler , reducer, and dynomax pipes to go from headers into stock location.

Gonna miss the dumped duals but need to change for emissions inspection. 😒
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