yotapickup91

I have a 91 pickup 3.0 4x4 extended cab, and the entire factory exhaust is rusted to pieces. Im going to need to replace from the downpipe back. Im not looking for performance gain, some fuel economy would be nice, but mostly i want to keep a tight budget. Bosal seams to have to best ready to go system, for a decent price, but im unaware of the qualiity and dont want to have to dig back in to it in a couple years. Also, even with Bosal, the cat is the most expensive part, at atleast $100. But i found out that a high flow cat from magniflow or otherscan come in at around $50 and should boost power a fuel economy a bit, i have access to a welder so im wondering if thatd be the way to go. Or, since i live in an area void of any insoections or test if i should just remove the cat(or just cat guts to maintain correct lenghts for mounting). But how would this affect the O2 sensor? Im open to any suggestions.

93Xtra-Cab

I was in the same predicament about a month ago. If you don't have state inspections and/or emissions testing, get rid of the cat. It won't affect the O2 sensor. I just finished my new exhaust last week. I removed the cat and installed a straight pipe and a Magnaflow 11235 muffler. Sounds great and has no loss in torque. Don't expect any gains. They're marginal at best. Fuel economy is about the same, even though I'm driving it harder than usual. I bet if I go back to driving it easy, my fuel economy might be a little better. Total cost was a little less than $120. For probably $45 less, you could install a turbo muffler. This is if you do the work yourself.

Oh and I have the 3.0L v6, just like you

85sr5excab

If u build it yourself make sure u get aluminized pipe or it'll rust out in a year or 2.

Mr.Cheekers

I have a 1994 Extra Cab pickup with the 3VZE. I Found A rolled over 2004 4Runner in the junkyard. I got the muffler, tubing and flanges for 50 bucks. I had to cut and tilt the muffler and hangers. Everything fit nice sounds good.

RSR

You can sell your stock cat for at least $150 provided its core is still intact (usually closer to $175-180 I think). It uses more expensive precious metals than are in the newer ones...

3vzes run rich so the more durable magnaflow metal core is probably ideal compared to the cheaper but less durable ceramic core, one of those paying for it twice things if cutting corners... The magnaflow ceramic high flow is paid for by selling your current, and the metal core is roughly 1/2 to 2/3rds paid for by selling your current.

On the 3vze exhaust, I think about 1/2 of the possible performance gains are in a proper mandrel bent cat back w/ high flow muffler, 1/4 in the cat, and 1/4 in the headers (but much of that header benefit I think can be found in a crossover delete...).

LC Engineering makes a stainless steel, mandrel bent cat back kit for our trucks for ~$400. Add in the cost of having your exhaust shop weld the sleeves and you're only at $450. IMHO, that's the way to go if you plan on keeping the 3vze/not swapping. It's just straight pipes from the collector back to cat, so your exhaust shop could replace the stock 2 1/8" pipe w/ 2.25 or 2.5" pipe to cat w/ little change in performance due to being mandrel bent. I think I would go 2.5" from collector through cat (get the 2.5" cat w/ same dimensions as stock) and have your exhaust shop replace the 2.5" out flange on that cat with a a 2.25" flange (they'll crush slightly to make it fit, but the cat is a big restriction in the exhaust so anything that increases flow through that point is good) welded to cat out pipe to connect to the LC Engineering kit from there back. Should be able to do the whole thing for $600 and it'll actually last and give you a significant improvement in performance relative to bosal, etc. Heavier piping too, and it won't rust. And the improved performance applies to both MPGs and power, so it should pay for itself. The Bosals are aluminized steel and lighter gauge steel, so definitely are not as robust. And they're also crush bent, which means more restriction/reduced performance.

*The reason for smaller to larger is that hot gasses expand, taking up more space, and the route above allows you to save some $ by only buying the pipe size you need, while keeping exhaust gas speed consistent throughout the exhaust pipeline (speed is the key to an optimized exhaust). And it's why modern cars also go smaller to larger (saves money w/ no affect on performance). And unfortunately on our trucks, no exhaust is optimized for the 3vze. They're all for 22re... If going to a 3.4 swap eventually, you'll want the 2.5" exhaust throughout... But if building for the 3vze, a 2.25 cat back should be fine due to gasses cooling and a 2.25 likely beats a crush bent 2.5 exhaust too... (If crush bending, you need to do some math and calculate the diameter of the crush bends and size up your pipe to where the crushed area equals the area of a straight 2.25 or 2.5" pipe)...

And mandrel-bent cat backs in the 2.25 size alone have been cited with up to 20% increased power and 10% increased MPGs. Even if those are exaggerations, you still have pretty big gains with just that as the first step...

RSR

Even without emissions, it's still illegal -- a federal crime -- to remove your Cat. And it's not uncommon for state troopers and the like to peek under, especially raised, trucks with louder exhausts and see if they've removed the cat and, if so, to issue a ticket, even if state inspections aren't required. So at the minimum, I'd install a "test pipe" in place of the cat should you have to put one back on. Just something to keep in mind as you make your decisions.

Masshole

Thanks for posting this!!! I need to replace my OE exhaust ASAP, it's looking like swiss cheese. My plan was to go stainless. Found a good deal on Magna Flow from header back, but I cannot for the life of me locate stainless bolts/nuts that are required! Now in my simple mind, I assume that stainless bolts would be preferred, mainly because of the rust issues. Does anyone know a supplier for stainless??

85sr5excab

My work gets ours thru fastenal. If u don't have a store in ur area then u should be able to find them online with a lil searching.

aztoyman

Since you can weld you can build a pretty cheap system yourself. Summit Racing and others sell mandrel bends and straight pipe as well as cats and mufflers.

Ace hardware sells stainless hardware in SAE and metric.

I don't have a 3.0 but as an example I built my system for my 3.4 swap in my 88 with two 45 degree mandrel bends, one 4 ft section of straight pipe, a Magnaflow cat and a cheap muffler. All 14 and 16 gauge aluminized tubing. And free shipping for ordering a Magnaflow cat.

You can spend more on stainless if you want.

Masshole

I'm willing to spend more to not have to replace the bolts and/or gaskets annually!! Thanks for the "Fastnal" idea, Ace is the place was my 1st stop, didn't have long enough bolts and nothing but nylock nuts for the headers.
Was hoping someone sold a kit so I wouldn't need to search the countryside!!

Tbrown0102

fastnal is a great source for alll kinds of bolts for sure!