Hey all. I have had my car down for 2 weeks as my Cat is starting to lose it. So I ordered one of those bolt in, straight through Cats that many places are selling. It lists as built for a 90-99 Nissan Sentra and is also listed as a 2.25" unit. The local shop calls the business selling these and while I'm standing right there, he asks what internal diameter it is and is it also for an SE-R. Reply is simply 2.25" and yes to the SE-R... I think you blokes know where this is going... So the business takes about a week before shipping it so it arrives today. I get to the shop, look at the outside (nice) and then look in..... WHAAAAAT?????..... Oh yes, it's 2.25" at start and exit, but can you believe, it's 1.25" in the middle!!!!!! My factory exhaust is not even that small. I will bet my life that the factory Cat can flow about 200% more exhaust then this thing. I was told 2.25" straight through and I get this shyte. I'm hoppin mad right now. I told my friends at the shop that I refuse to own this junk and that they need to send it back..... Ok, I'm done.... just don't buy one of these straight through Cats. It's a waste of time & money.

Cossie

Just throw a nice piece of 2.25 galvanized pipe in there.
You'll be alright.

cossieturbo, what part of florida u live in???????

If u want a Custom cat, get one from Andreas Miko in Kendall.

First he gut out the Cat, than he bring it to a Muffler shop near by to let them Weld a pipe in there, so now basiclly the Cat is just the look

I think he charge like around $50 dollar to do it. This will defenally free up some horsepower up top.

Just give him a call when u are ready.

His cell is 305-282-3643.

Good luck!!!!!


:) :)

Just a little tidbit from the www.se-r.net info:

The OE cat is of good design and is huge for a 4 cylinder. The inlet and outlet diameter is 2.5", with the inside growing to 3". Aftermarket cats might get to about 3", but you would have to have a 3" exhaust to make it work, which would lead to a very loud SR20DE, and I don't think you will gain that much. Either leave the stock one alone, or take it out for use on the track.
... [after] prolonged runs the OE cat seems fine even with various mods like cams and headers.


and another tidbit of info from Mike Kojima:

Unless you are turbo or run a large nitrous unit and are going for the maximum in power, do not bother with removing or gutting your cat. Unless the cat is melted it only has about 1.5 psi of backpressure or less and only affects power by 1-2 hp if that. This is even with a built NA motor. With a turbo or NOS you will lose some power. Remember, this (gutting the cat) is also a big time violation of federal law! Gutting the cat will cause a MIL light on post '95 Sentras which is to be avoided come registration time. There is little to be gained with aftermarket cats either, although they are priced well and if you need to replace your stock cat they can be a good value.

The Nissan OE cat is one of the best out there and there is really no reason to replace it unless your cat is clogged up due to many years of use and carbon build-up, etc.,
your are going turbo or are running larger than 2.5" ID on a NA SR20DE which is highly unlikely.

Just my thoughts as well as others proven results.