What downpipes mate up to Apexi N1 Catback?

[larryd]

I want to get the Apexi N1 catback for the GSX but I want a 3" downpipe this time instead of the 2.5" downpipe that Apexi makes. Does anyone know what other downpipes will mate up to the N1 exhasut?

 

[j_woody]

apexi does make a 3" dp

http://www.turbotrix.com/parts/exhaust.shtml

go down to downpipes and it is the 4th pipe down

 

[larryd]

its only 3" after the flex section, the first half of the pipe is 2.5".. thats the one I had before.

 

[gsx_power]

rre makes the long downpipe that bypasses the cat like the apexi. it goes 3" after the flex section too. they said that 2.5" is plenty room for the exhaust to exit through the bend and flex. buschur racing has the 3" dp, but i'm not sure if it's a true 3". have to ask them about that.

 

[larryd]

id really like to get the kind that has the removable test pipe.. but if I cant find any Ill prolly jsut end up getting the Apexi N1 downpipe again.

 

[Brandon92DSM]

I think the N1 frontpipe is the only one that will bolt straight up with no fuss. Lots of places make true 3" short-pipes that have room for a cat. you just may need to have a muffler shop help you piece it together.

 

[RnR Racing]

Larryd, I would like to suggest to you a 3" 02 elim downpipe. We make along with a few other compnaies. From us they come in the short version with a test pipe or the long version to eliminate the cat. The 3" 02 housing will greatly improve your spool up time. Any true 3" 02 elim will out flow a ported unit with ease. With a 3" 02 housing you will see a big difference.

We also make a standard 3" downpipe which is a little cheaper. It is a true 3" downpipe and there is only a 1.5" section of 2.5" pipe right where it mates to the flange. Let me know if there are any other questions,

I always recommned the 3" 02 elim because of the difference people see.

 

[ChicagoGSX]

Get an ATR O2 eliminator DP, take it in and have a 3" flange put on, and then buy a 3" test pipe from any of the places online. Only thing is the ATR DP doesn't have a flex section. I've had no problems with mine however. Just make sure the test pipe you get has the same flanges as the Apexi catback.

 

[Compressed]

Yeah Larry, with your setup I would definitely reccomend a 3" o2 elim. I've heard very good things over ported o2 housings.

 

[j_woody]

correct me if i am wrong but doesnt having any section of the pipe shrink down (say to 2.5") even for just a few inches basically negate the fact you have a 3" exhaust system? if you had a 2.5" turbo back would it flow just as good as the 3 incher that drops down to 2.5 for a couple inches? I have heard numerous times exhausts are only as good as their weakest link

 

[RnR Racing]

The standard 3" downpipe is 2.5" at the flange where it begins so it will bolt up to your 02 housing. You want the downpipe to begin the actual 3" piping asap. On some 3" downpipes it doesn't actually become 3" until after the flex section. I was just pointing out that our 3" downpipe is a true 3".

 

[DSMu4ia]

Unless that VP 02 housing you got is a 3" one (which I don't believe Scott is making), you will still need a 2.5" flange welded onto your downpipe.

Not alot of people understand that a true 3" turboback, includes the 02 housing, and the downpipe.

Majority of people just have 2.5" 02's, 2.5->3" downpipes, and 3" cat backs.

 

[candela]

Larry,

This is the only true 3" o2 and DP that I really know of. Its not like theres a huge advantage to what RnR makes or anything, but it is pretty nice IMO. This is my nice and dirty 3" o2 back extreme exhaust http://www.dsmtuners.com/gallery/showphoto.php?photo=7788&papass=&sort=1
Im not sure what it bolts up to but I do have a removable test pipe on mine I got pretty shitty customer service from these guys but the product is pretty good. Id try and get ahold of them to see what the DP/testpipe will mate up to (N1?)...


Austin

 

[larryd]

well guys i appreciate the information.. I cant go with an o2 eliminator.. I have a VP o2 dump tube with the mount for my tial external wastegate.. so an o2 eliminator wouldnt quite work ..

I think im just going to go with the Apexi N1 downpipe and not worry about the 2.5" section before the flex pipe.

 

[4g63tc]

larry chek out www.osofastracing.com it's brent rau's web site he does have a pretty nice dp for the price. i'm getting one for my gsx

 

[4g63tc]

the 3in.

 

[4g63tc]

2 1/2 if interested

 

[zac83]

hey larry, i was shopping for exaust recently too: someone at a rather respected DSM shop in california gave me the number to a reputable machine shop in the area that will fab or does make 3 inch full downpipes/o2 eliminators.... gooood stuff, 3 inches all the way out, no BS 3 inch systems. call RRE up and ask them for culvers number and tell them what your looking for.

 

[VBGSX]

Hey Larryd....check the size of your VP dump O2. If it's 2.5 then either RNR_Racing's or the osfast racing DP that 4g63tc posted would work greak. Both have the 2.5 flange which will attach to your O2 housing and then expands to 3in about 1.5 inches from the flange. What's 1.5 in.s if your O2 housing is already 2.5in.s
Then all you would need it to get two flanges and make a test pipe.
Just a thought

 

[Brandon92DSM]

Originally posted by j_woody
correct me if i am wrong but doesnt having any section of the pipe shrink down (say to 2.5") even for just a few inches basically negate the fact you have a 3" exhaust system? if you had a 2.5" turbo back would it flow just as good as the 3 incher that drops down to 2.5 for a couple inches? I have heard numerous times exhausts are only as good as their weakest link

I doubt its that simple.

You also have to take into account the fact that the exhaust gas in the O2 housing is hotter than the gas further down the line in the downpipe and cat-back section. I doubt an exhaust with a 2.5" section for a couple inches expanding to 3" would flow the same as a full 2.5" setup.