On my 93 P/U I anticipate rebuilding the engine at some point down the road, probably within around 2 years. At that time I am going to put an exhaust on as well. I have flipped back and forth in my mind about what I want to do is far as exhaust goes. The one steadfast I have in my mind is I want a Borla Turbo Muffler. I am not going to waste my time going the headers route. It's just too costly I feel (and from the impression I get) for what you get. My main reason's for doing exhaust are to smooth out the power band a little, for a mild power increase, and mild gas mileage increase. I also bet that an exhaust will help move heat a little better out than the stock system currently does which will help reliability.

I've heard a myriad of different things guys have tried plumbing a catback exhaust, to a complete exhaust system. I've heard a myriad of opinions from this board over the years on what size is best, what mufflers are best, etc.

First what I want to ask you is what is the stock exhaust size, from the stock header/manifold, through the cat, to the muffler, and out, back? Didnt someone say it was 1 7/8" diameter tubing the entire way?

I think my stock cat is in relative good shape so that may set the stage for just doing a cat back. But I then I think I should consider a bigger size diameter flowing cat since I want to up the size of the pipe and would rather do the whole thing and not just a catback. Lots in here seem to like the carsound cats. I was considering looking into a stock cat off of a 3.4 V6 Tacoma. Does anyone know what size these cats are?

Next, about exhaust size. I've heard a 2 1/4" system will produce a slight loss in low end torque but better kick in the higher rpm's. Lots of guys, from the impressin I get, run 2 1/2" systems with headers. I figure that if I run a 2" system with a new cat and a high flow muffler like the Borla I can probably keep the torque, and get a little bit more, and gain alittle bit in the higher end. Borla advertises typical 5% gains with their mufflers.

Next thing I'm curious about is what are your guys opinions on what type of pipes to go with. I will go the mandrel bent route only of course. Is stainless steel worth the added cost? Is there a healthy medium that will survive? The Stock exhaust system & pipes which are aluminized if I recall seem to do reasonbly well and are usually good for 120,000 plus miles with out any problems, at least where I live where we don't salt the crap out of our roads, only mildly with the odd frost and such.

 

mines aluminized mandrel bent 2.25" with headers seems to work well, theres more power across the board. I'd go with headers but thats just my opinion, seeing that my motor went due to a burnt valve on #6 I decided to get the extra heat away from that cylinder by putting on headers. I've got a stock cat but will be replacing it with a carsound when I have the money. I didn't notice any loss down low when I put on the 2.25" cat back prior to the headers but did gain some above 2500 or so.

 

I have a stainless Borla cat-back on both my 4Runner and my JGC. They are both GREAT! I'm using standard cats on both. Although the 4Runner will likely get a hi-flow model prior to finishing my swap.

 

A lot of people don't do it but I'm gonna run a progressive system. 2.25 y pipe 2.25 to a 2.5 muffler and then 2.5 all the way out. I've been told that this gives the best results. I'm gonna do headers after I have all the other mods done, that way I can see just how much of a difference it makes over the Y.

 

If you're already going to have the engine out, put a set of headers on there. The crossover pipe is just plain stupid, and I too had a #6 valve burn. Shouldn't happen again w/ the headers. Pretty good power gain. Had a local muffler shop weld up the connections and make the rest of the exhaust from 2.5" NOT mandrel bent tubing (cheaper and effectively the same as 2.25").