After searching 2 years worth of exhaust posts, I still have 2 questions -

Is the stock pipe size on a T100 exhaust system 2.25" or less? From the manifold to the exhaust tip, where exactly am I losing back pressure (aside from a leak) by going with the larger pipe? The exhaust system on my truck - 3 inch Walker Hi Flow converter, 3 inch aluminized pipe to a Walker Dynomax Super Turbo muffler and 2.5 inch side exit.

I've traced a small exhaust leak to the fitting before the muffler and before I bother to weld it, I'm thinking the 3" pipe is robbing my low end power and S/C, from the loss of back pressure. I may replace the pipe if possible and someone can back up my theory. The lack of initial throttle response compared to a friend's S/C'd Taco, with a stock exhaust, (taking into account the weight difference) has me thinking this system is the culprit. I appreciate any help as I try to figure out my next move -

3" pipe sounds a tad on the big side. Sizes like that are generally for turbocharged and/or rotary engines. With turbocharged engines, the turbo itself provides all the backpressure you will ever need. Rotaries just plain don't like backpressure. I would guess somewhere in the 2.5 inch range would be more appropriate for your setup, but I'm no exhaust expert.

i had read elsewhere i think it was on yotatech , that the biggest you should use on a 3.4 L was 2.25 , i cant remeber why or who figured it out , but i do remeebr reading it , so take it for what its worth.

airrikk17

When I bought my TRD header and cat-back, they had two options on the cat-back 2.25" and 2.5". I told the tech at TRD that I pulled a boat and wanted the best setup. He said their header teamed with the 2.25" cat would keep the low-end intack on my non-SC engine. Brew <img src="/forums/images/graemlins/cheers.gif" alt="" />

I'm going to throw in my two cents here. I've had a s/c Tacoma in the past and currently have a s/c'd 4Runner. The thing to keep in mind is that exhaust diameter is more crucial in normally aspirated engines. There are tons of posts on the web about the subject. A supercharged engine is a completely different animal. Since you are forcing more air into the engine, you need to remove that air much more quickly. I would say that your lack of low end power is more a combination of fuel and timing. Before you go ripping off your old exhaust, I would put the money into a fuel system upgrade. I know that people will argue that a stock 3.4L engine will adapt to a S/C just fine. Heck, my Tacoma ran absolutely tip-top with the just the s/c and no fuel upgrades. However, my 4runner runs 5 times better with the fuel upgrades. By better, I mean more low end torque, winds up faster, and just plain pulls harder.

My advice is to invest in the URD fuel kit for your truck. You'll be amazed in the difference it will make. Good luck with your decision, and let us know how it turns out.