Hey check this out. He was sneaky and custom fab'd 2 cut-outs into the 3 inch Y pipe he built. I didn't know until he sent me this picture. I love it!

 

Looks pretty good.
What would be the length from the collector flange to the cut out flange? It looks like you might be pretty close to the proper length secondary/collector which makes ALL the difference in power output when running open headers.

 

I couldn't tell ya skinny z. The best bet would be to approximate from the picture. The driver's side appear to be longer (on the left side of picture). I wish I could give you a better answer but the car is an hour and a half away.
Regardless of how proper, it's definitely better than having no cut-outs which is what I was expecting. He didn't even charge me for the cut-outs or the extra time it took. Hopefully he will throw in the plates that bolt on! LOL Either that or they'll be $250.

 

The only reason I've mentioned it is that so many forum members have commented on how terribly their vehicles perform with open headers. In all of those cases (as far as I'm aware), the collectors are opened right at the flange which leaves a secondary length that's WAY too short for anything but a Pro Stock engine. Low engine speed torque suffers dramatically and the cars fall flat.
Yours on the other hand look like they might work to improve performance when you decide to uncork.

 

I see what your are saying ^^ The longer the pipe the more torque you will make and if your cutouts are too soon Bybye torque hello obnoxious noise

 

Somewhat, yes.
The spec of the engine determines what length of collector is needed. A highly strung racing engine will need a different length secondary than a milder street engine. The tendency is that the higher the operating range, the shorter the collector needs to be.
This explains why the street engine feels so lame when you're driving it to the muffler shop with open headers.

 

very nice work!

 

most of the time it's in the ball park of 8" to 15" long after the flang.
dep on eng and parts

the best way to tell. is install a 15"long x 3" tube to each flang.

use some cheap white color paint. on the tube. at the track. just make a run down the track not much of a burn out. just a full power run.

shut it down at end. Now. if you look at the tubes you will see how it turned colors.. cut tube 1/2" past color diff at open end of tube. your done

thats a nice set up..have the same type myself

 

judging by the 8 inch tall hollow blocks that make up the wall and allowing for curves in the pipes, I would say one side is about 16 inches and the other is maybe 21?
I see what you are saying though about the torque. The cam is a torquer V2 that's pretty much middle of the road and should make power up to around 6,700 or so and kick in around 3,200 or 3,400.
I won't be running with them open anywhere but the track, well, maybe except special occasions that involve mustangs. I will make sure to run it both ways to see what difference it makes.
I had 1 cutout after the y on a sbc, trick flow heads, fireball cam, 700r4, 3.42 posi, 87 firebird years ago. It was consistently 4 tenths faster with the cut-out open. It also had smaller pipes though. I think it was 1 5/8 headers into a stock 89 GTA Y pipe and cat-back.
I just realized it was my current GTA's stock cat-back

 

Now THAT'S old school. Been a while since I've heard someone mention that technique. Pretty effective from what I've heard too.
On the other hand, I've invested in the PipeMax program. I'll have to see if science gets better results.

That's encouraging. I'm running a single 3" y-pipe into a stock location muffler. I'm positive it's KILLING what ever potential there is this combo. Even my simulation programs show the dramatic improvements from a zero backpressure exhaust that has some tunability (via the collector extensions). 4/10's is a huge gain.

 

how close would these cutouts be to a cat? I'm going the route of cutots, and something like this is exactly what i was thinking, but i read to get the best performance, most third gens need the cutout at the cat.

My cars in storage for a few weeks so i cant check my own, but would the cutouts being there in the y pipe hurt performance compared to only having one at the cat? Or i guess i should say throw off the right amount of backpressure and airflow?


Anyway thats a cool thing your mechanic did, im sure it will have a great improvement over the stock exhaust.

 

I understand what you're saying so yes, it looks like he did the right thing. One possible drawback though. Maybe a little less torque down low would be a good thing with my GTA. She's gonna be a handful. lol

 

I don't know that I can answer your question very well. Mine isn't a stock 3rd gen engine and it won't have cats. If I were in your shoes I would put a cut-out right before the cat or in place of the cat. That's assuming you are running the stock engine. Whether or not you are running headers (and which ones) and what size pipe your y is should make a difference too, along with mod.s and what cat-back you have. A great flowing cat-back will not gain as much from cut-outs as a stock one or flowmaster.

 

It was all torque. The car went 13.7's at 102 on terrible street tires and a 2.2 60 ft (wheel-hopping and getting sideways hitting second gear- THANK YOU SHIFT KIT) thru the muffler and 13.20-13.40 at 103mph with the cut-out open. I never put sticky tires or a stall on it even knowing it would hit 12's if I did. I was afraid of breaking the rear end.
The kid I sold it to asked me to go to the track with him and teach him how to race it. After having him ride along for the first pass and explaining to him why Not to go thru the water box OR do a monster burnout, he jumped in, ignored me, put on a smoke show, and then broke the sprag in the transmission off the line.

 

Ugh.... some kids....

 

same kid wound up going to school to be an auto mechanic. Good thinking