2-1/4 downpipes vs. 2-1/2 downpipes...

FineLineMtrSprt

Registered User
Sup folks...let me give you some info on the SC i picked up...

89 5spd
10% pulley
CAI
3.55's
gutted stock cats with cut and welded stock midpipes
3in borla muffler with single 3in exit behind left rear wheel....an thats it

So yes the total system needs work.

Heres the plan

Super coupe performance highflow midpipe WITH highflow cats..
keeping the 3in borla...running duals to stock location...
adding 2 dynomax welded bullets in stock muffler location with stock style turndowns.

With that set up i hope to take away some of the raspyness while still keep it legal with cats ...getting ride of nasty smell when cold...and having correct dual exhaust. The midpipe is 325 bucks....its pretty much the best price i can find unless you guys know something better. Now this being my first v6 in awhile im not sure if i should go witht he 2.5in mid mipe or the 2.25in midpipe.

What do you guys think....anyone have any expriance with these pipes from Super coupe performance....anyone have any sound links..or vids you have taken with your own car and something close to mine. Just let me know,

Vince
 
My main thing is i dont want it to sound like azz. The midpip with no cats is 195...with cats its 325..i guess i could get the one without cats and if it does sound too much like crap get a pair of high fow cats and weld them in...i still would come out around 325 bucks. I also kinda wanna get that "no-cat" smell out of it too lol...so i guess that means high flow with mid pipes....i dont know lol
 
im not sure bout the ones for an sc but i have learned that highfolw cats give basicly the same smell as no cats
if you talking about that almost rotten egg smell ha ha
but like i said i have no idea about with the system your looking at
 
cross sectional area for 3" is 7.06 sq inches.
cross sectional area for two 2.5" pipes is 9.8 sq inches.
cross sectional area for two 2.25" pipes is 7.95 sq inches.

Seems like either combo will outflow the 3 inch section. If there is a big difference in price, i would just go with the smaller ones.
 
im not sure bout the ones for an sc but i have learned that highfolw cats give basicly the same smell as no cats
if you talking about that almost rotten egg smell ha ha
but like i said i have no idea about with the system your looking at

I like that smell :rolleyes:

My exhaust sounds good except for LOUD resonance around 1500-2250 RPM under load. I have 2 1/4" downtubes, Carsound 2 1/2" cats, Magnaflow X-pipe, and 2 Dynomax Superturbos. I'm going to put a D/D Magnaflow muffler in place of the X-pipe, hopefully it'll quite that resonance down. I guess I'm one of the few guys that did 2.5" dual all the way back, at least from the cats back.
 
My main thing is i dont want it to sound like azz. The midpip with no cats is 195...with cats its 325..i guess i could get the one without cats and if it does sound too much like crap get a pair of high fow cats and weld them in...i still would come out around 325 bucks. I also kinda wanna get that "no-cat" smell out of it too lol...so i guess that means high flow with mid pipes....i dont know lol

I think you are using the wrong term. Down pipes connect the exhaust manifolds/headers to the resonator. The mid pipe is the single pipe normally located between the resonator and the mufflers. Since you mentioned getting them with or without cats, I'll assume you are actually asking about the down pipes, especially since that's what is mentioned in the title of this post.

For your mod level the 2.25" down pipes will work best.

David
 
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I would go 2 1/4 downtubes, highflow cats into a magnaflow resonator

Now either go single3 inch or dual 2.5's out back

if you go single 3.5inch you can get away with single all the way back to one muffler...Or you can go 3.5 into two 2.5's for decreased sound level

On my teal SC I have headers -2.5 inch high flow cats into a flowmaster resonator with 3.5 inch back into two dynomax mufflers....

ITS VERY QUIET
 
Thank you all...and yes..im used to calling them midpipes since thats what they are called on stangs and Lightnings. Ive run high flow cats before...and ive run no cats before...there is a SLIGHT difference in smell...kinda like unburnt fuel....but oh well ya know. Im really considering the 2.25 in downpipes with highflow cats...leaving the 3in Borla Xr1 as a resonator and then doing two Dynomax bullets in stock mufflr location.....and if anyone knows what bullets im getting....they are pretty much just a metal shell with slight preforation inside..so there wont be much sound loss. Hopefully in the next couple weeks i will have this thing all ready to go...belts..upper and lower control arms...new ford coil...souple sensors...engine mount are all going on soon. I installed the new IAC and it helped the idle some...but after driving it a bit and then letting it sit..its hard<cranks for a bit then stumbles> to start hot. So im going to try the coil. I seriously thank everyone for the help and will post pics and vids as soon as i can.
 
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