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Mike
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I'll be running my short deck 11.2:1 572 at the track once a month shift point 72-75 hundred. Right now I have 2 1/4" headers with 4" collectors. Will a 3.5 exhaust with an X, and 22" Magnaflows cause much of a reduction in ET. I have moved the tires in and I'm not sure if I can use tail pipes, but if I do They would either be 3" or squished 3.5s, or ended at the axle. I could also use band clamps and pull the exhaust, just trying to figure out which way to go. Thank you.
 

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Have same headers as you and reduce to 3.5" pipes and 3.5 Borla XR-1s that stop at axle, no X pipe. I would be interested in the difference as well. I haven't tested back to back.
 

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I have slightly larger cube and took 3.5 all the way to the bumper. 2 1/8 stepped to 2 1/4 x 4" collector....Don't have any times yet for comparison (open headers) so no help there.

If I didn't street drive the car I would have kept it in front of the axle, but that got-damn drone was blurring my field of view & my periphrial vision !! Heh, I can actually have a conversation is the car now while driving it ?? Crazy.......:rolleyes:



Am I getting old...:smt102
 

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Old guys rule!
 

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Have same headers as you and reduce to 3.5" pipes and 3.5 Borla XR-1s that stop at axle, no X pipe. I would be interested in the difference as well. I haven't tested back to back.
Which Borlas are you running, the 12" or 16" ovals or the round?
 

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Just another idea...

I run 3.5 ovals back to a X pipe then into 3.5" oval Borla XR1's.
Then immediately into custom Spintraps with a 3.5" oval inlets and two 2.5" rounds outlets.
The two 2.5" rounds have more flow than the 3.5 round and route easily over the axle and out behind the rear wheels, like a stock 70's Trans Am.

I can unbolt the system at the rear of the Borla's and still be muffled for the track.

This system is extremely low profile and fits tight under my 70 Camaro. Even the exhaust tips are pretty much hidden.

The Borla's alone drew too much attention from the local constabulary!

Roy
 

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Where are you getting the bigger 4+ pipes?
Trucking places carry 4 inch to 5.5.we have bough oval stuff and cut it and added to it to make desired area.we have made our own mufflers also.5 inch is mellow sound compared to smaller high pitch .jmo .but we have tried allot of shit through dyno sessions or street cars.high hp blower engines a bitch to get streetable .we do oval now for ground clearance.
 

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I agree with the 4'' I have 4'' with Magnaflow ovals on my baby 489 and its only about .005 slower than open. The evac system works great too with the exhaust on. Weighs about 52 lbs dumped in front of rear.



 

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Aukai
wish you lived near me.we have all kinds of shit laying here for our chevelles .bet we could throw car on hoist and try several combo under your car.i have 4 inch on sbc would think your engine need at least that.jmo
 

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do u have a video with sound on the 55? would like hear it
 
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