Performance Headers and Exhaust?

So, I bought a Tacoma and the cat was clogged which blew part of the gasket for the right side header. Since I'm gonna be pulling off the header to replace the gasket I thought what the hell and put performance headers on. So I looked around on parts sites (including URD) and YouTube to see what was the most common with the least complaints if any, I found Doug Thorley to be the most common. Is anyone running these on there 3.4?

For the catalytic converter I need to be California compliant (seeing how Washington adopted there emissions standards now ) Magnaflow seems to be the most common 50 state legal Catalytic converter but is there anything else anyone has used and passed emissions?

Finally since I'm gonna be running performance headers and a high flow cat should I stick with the stock 2.5" diameter exhaust tubing? Or bump it up to a 2.75" or even a 3"? I'm running a FlowMaster 40 series muffler.

I'm looking to boost my performance without making my mileage suffer, but only increase.

Experienced based post please? I need to pass emissions soon and need real life evidence that its worked and passed on your truck.

Thankyou

 

Keep it at 2.25" pipe. That's stock. You'll loose Lowe end torque and power opening it up. Unless your boosting, I wouldn't go to bigger pipe.

Can't speak on an emissions stand point...don't have that in Wyoming

 

Exactly. Big pipes are for boosted applications. A small amount of back pressure is needed for NA engines.

 

Planning to run the gen2 trd supercharger in the future. would it be worth opening to a 2.5" now? Or should I just keep it at 2.25" even after boosting?

 

you'll see a power loss until you boost it

 

for what its worth, on my 2nd gen i had(4.0), i removed the rear 2 cats, and redid the exhaust with 2.5" tubing mandrel bent or pie cut and tig welded (no kinks in tubing). did 2.5 into the muffler (magnaflor 24inch) and 3" out of the muffler.

i saw no loss in power, and only a very slight seat of pants gain in the mid range.

that said, i would not go bigger than 2.5 into the muffler with a 3.4. But if i was paying the bill, i just keep it stock size tubing( 2.25 i think) but have a non kinked layout to help flow just a little bit, slap on an 18-24" long muffler (partial to magnaflow myself, keeps the sound down and not raspy like a flowmaster does) and do 2.5 out the back

 

I'm running TRD S/C with TRD headers to Borla 3" cat back.
Since 50,000 mile mark.

Just turned 305,000.

 

Alright Ill keep it at a 2.25" from the cat to the muffler & 2.5" tailpipe