So my experiment with test pipes (resonated and non resonated) and Y pipes went pretty good.. however I will preface the post by saying I DESTROYED my stock exhaust.. all the mods mentioned below had the stock system attached.

I purchased some top speed resonated test pipes a while back..
installed them.. Installation was pretty simple really. the major thing you need is the 24" extension from autozone ($11 bucks)

the sound was ok.. rasp was there. but not super bad..
track.. the car went 13.86 at 101 with a superb 2.086 60' time on fully inflated street tires..

after 3 mos... they cracked at a seam (not a weld, but where the resonator was bent to form the cone) and I ditched them in favor of the stock cats and a Nismo Knock off 3" outlet Y pipe..

sounded great.. noticed a little in the seat of my pants.

enter the HELIX testpipes non resonated. + Y pipe

SUPER RASP.. track again.. too cold.. couldnt hook up.. posted 102mph traps and worse times than before..

well.. after about 3 WEEKS of driving on this high flow till Y-back exhaust, the vibrations from the 3" of exhaust SLAMMING into the 2.5" inlet of the rest of the system caused the WHOLE exhaust (except Y PIPE) to implode.. literally DESTROY itself..

first round - after the flange on the Y pipe and after the flange on the center exhaust pipe the system BLEW a HOLE the width of a quarter and the height of a thumb nail out of itself right after the weld on the center pipe. the system then proceeded to rip itself after the seam like soemone hit it with a hack saw.. perfect circumference.. right in half..

welded that noise up..
1 day.. wham, it came back.. this time.. it was the TESTPIPES that had self destructed..
crack ALL THE WAY AROUND at the bend on the passenger side testpipe and it blew the o2 bung 3/4 out of the pipe.. astonished, I welded it..

1 day after that.. it came back.. this time in the rear of the car... the stock system QUIT.. it ripped itself right out of the main muffler in the rear... so its just sittin in the big rear muffler.. haging out being all loud...

then I quit.. put stock cats and Y back on with the damaged rear exhaust section (doesnt sound too bad, sounds like a catback is installed)

the moral of the story is.. DO NOT I repeat DO NOT get a Y pipe with 3" outlet if you dont have a 3" catback..
I KNEW this could potentally happen.. I just ignored it..

ALSO.. When checking drag times... I noticed that some Z's trap in the 103-4 range.. what did they have in common? ALL of them had cat back exhaust systems..

looks like its a great investment.. and it will open the gates for more, beneficial, modifications in the future.

I HIGHLY refer the Y pipe that is on Nissan Z Trader right now by the seller CarNRace.. here is the LINK TO Y PIPE
the thing is built like a TANK.. and was the only part of the exhaust that did not self destruct in any way.. not bad for 100 bucks..

 

Sorry....I'm lost.

 

Correct me if I am wrong but would having a 3" outlet on the y-pipe mated to stock catback create a significant perturbation in the exhaust flow? Efficient exhaust is all about flow. Mating 2 parts like that creates a abrupt step in the piping, at the flanges since you have a large opening violently changing to a small one...which is bound to kill the efficiency. Just thinking out loud. I imagine going from small to large is not as bad although not really optimal either.

From experience, best way to keep EGTs low is to have good flow. If you allow the gas to stick around too long, you end up building up good amounts of heat which can cause all kinds of issues. My bet is your setup had poor flow dynamics which caused all kinds of irregular heat zones. Metal expands and contracts as it heats/cools. Things started to twist and pull on each other due to thermal conditions, add vibration, and you saw what can happen.

Moral of the story: it's a bit more complicated than just slapping parts together to create an efficient exhaust that won't implode

Good post.

 

Pics? Where can I haz?

 

Exactly..
exhaust flow was slamming into the stock 2.5" system heating, and shaking it apart.. it self destructed because I made poor choices in getting testpipes and a 3" out Y before I got a catback..
it has to be pretty damn violent to shake a whole exhaust system apart..
thanks for the props..

 

Picz? Haz?

 

while ever so cute and cuddly, I think you can stop with the cat pictures. I'm in for pics too considering I'm getting test pipes/HFC's soon...have yet to decide which, and I wanna see what my future looks like. I on the other hand did it right, I have a catback already....live and learn.

 

fixed

 

I laugh my *** off when i see that cat..
I dont have any pics readily available..
I can get them, but it wont be for a while..
just trust me when i say, GET A CATBACK before testpipes/Y pipe.

 

 

hahah Isnt cat back mean from the cat back?