Y-Pipe options for '92 350 TBI

So I've periodically looked for upgraded y-pipes for my '92 Custom Cruiser, because I've read that on the 350 TBIs that it's an incredibly restrictive part of the exhaust. However, it seems most if not all of the topics I've found around the internet are referring to to trucks, and so I'm not quite sure if the parts I've seen recommended will fit. The part I am most partial to is this one: Link
However I do not know if it will fit my car. I've also read that I will need to upgrade to a 3-wire O2 sensor and look out for the EGR to make sure that stays working, but again, that was in reference to trucks and I do not know if it's the same for the cars. I apologize if this is a really rookie question, I'm only 24 and haven't really started playing around with cars until now. I'm not to try and turn this thing into a racecar, but from the sounds of things GM made the exhaust really restrictive to just heat up the O2 sensor, and I'd like to just upgrade it for the "free" power and maybe get a little extra mpg if I'm lucky.

Not to dissuade you in any way, but something else to consider is a full dual exhaust. By the time you either do the work to adapt the 2-1/2" inlets and 3" outlet to the stock pipes (or pay someone to do this for you), you'll be closer to a full dual exhaust than you think in terms of time/effort/money.

No O2 sensor changes necessary in either case that I can think of.

A "Y" pipe of that style would help the flow, but would require a number of other changes. You need a reshaped right and left down pipe, the 3" output would require either a larger diameter cat, and cat back pipe, or a step down pipe to fit the stock cat. If you step it down to the stock cat, you will negate the advantage of the "Y" pipe. If you upgrade to a larger diameter cat, you will have the cost of the cat, and the larger 3" cat-back pipe. The difference will not be noticeable except in the weight of your wallet. If you go to duals, you will not lose the EGR system, unless you put headers on it. Headers will
not have the EGR port. You can still run on a single O2 sensor in the left manifold, or header. If you choose to go to dual exhausts with the stock manifolds, you will maintain the EGR, but the exhaust will require another muffler, cat, and cat-back pipe. You will also need the heat shields for the tank, heat shield for the floor for the 2nd cat, and the trans crossmember must be modified to allow the pipe to go under it. It is costly if you have someone else do it for you. If you can do it yourself, it could be cost effective. The HP increase will be in the range of 20 for the duals. If you put headers on it you may get 30-40 HP. From there you are looking at different heads, cam, headers for sure, intake, fuel injection system, ignition, computer, and maybe a lot of other upgrades. If you have automatic load leveling, you will have to remove it for the duals. I was watching an episode of Engine Masters, and they put together a "Y" pipe system with a 3" exhaust beyond the "Y". It worked as well as a 2 1/2" dual exhaust. Just remember that the pipe must have an over the axle section, or dump in front of the axle.

The pics below are the first iteration of my duals, I have since made a straighter path for the left side at the trans crossmember, mirrored the right side to fit closer to the body beside the driveshaft. Floor clearance at the driver's side rear seat well is minimal, and I used the end bolt of the driveshaft loop to attach a hanger for the center of the exhaust pipe on both sides. As an aside, the duals will make changing the starter a lot easier.

Fix Until Broke wrote:

Not to dissuade you in any way, but something else to consider is a full dual exhaust.  By the time you either do the work to adapt the 2-1/2" inlets and 3" outlet to the stock pipes (or pay someone to do this for you), you'll be closer to a full dual exhaust than you think in terms of time/effort/money.

Would there be any reason to run something like an x-pipe on that or would it just be too complicated to make fit to be worth doing?

Fred Kiehl wrote:

A "Y" pipe of that style would help the flow, but would require a number of other changes. You need a reshaped right and left down pipe, the 3" output would require either a larger diameter cat, and cat back pipe, or a step down pipe to fit the stock cat. If you step it down to the stock cat, you will negate the advantage of the "Y" pipe. If you upgrade to a larger diameter cat, you will have the cost of the cat, and the larger 3" cat-back pipe. The difference will not be noticeable except in the weight of your wallet. If you go to duals, you will not lose the EGR system, unless you put headers on it.

My car is exempt from emissions here, so I could run without a cat, but I'm assuming that's ill advised. Are there any pros and cons of keeping the EGR vs ditching it?

With headers, the EGR code will post in the computer, and it may cause the computer to run in open loop at all times. The cat is only to negate CO and NO emissions. If you do not care, you can remove it with no adverse effects. You can run the 3" pipe to a muffler, and dump it in front of the axle. Removing the cat can give you a HP gain, as well as a low restriction muffler. If you put headers on it, make sure the O2 sensor is on the upper half of the pipe, and at least 18" from any leaks, and the end of a pipe, or it will not function properly. I put mine in the collector of the header, and have a dead soft aluminum (you can use copper) flange gasket on the collector joint. If you have a ball end, make sure it is air tight.

AFAIK, the converters also get rid of any unburned hydorcarbons also?