Texas Hill Country - Hidden Falls | 4th Gen Tacoma Forum

OTT High Flow Catted Down Pipe vs. OEM Down Pipe Side by Side

Quez · 2026-04-19T17:48:26+00:00

On the 2024+ Tacoma, the downpipe is the piece in your engine bay that connects the turbo to the rest of the exhaust. It’s one of the most restrictive parts from the factory since it also contains a catalytic converter (what everyone refers to when they say, "cats/catted/cattless." The most common reason people upgrade the down pipe (DP) to something like Overland Tailor Tuning's (OTT) DP is it is far less restrictive than the OEM DP. Less restriction = more airflow = more power. Like most manufacturers, Toyota's OEM DP was designed to be quiet, and emission friendly. With a high flow catted DP, there's larger piping & a less restrictive catalytic (cat) core. For the non mechanical people, that causes a reduction in backpressure from the exhaust and lets the gases exit faster. Once you have the reduction in backpressure, the turbo is able to spool faster, equating to less turbo lag & better responsiveness throughout the RPM range. Now, pair it with the OTT Stage 1 calibration delivered from Big Dawgs Toyota Tuning, you get noticeably more useable HP/TQ from your vehicle. In all fairness - adding a DP is a supporting mod when looking for more more. It's another piece to the puzzle. It can give you some gains, but I personally have not had my truck on the dyno yet to give an accurate number for this one specifically. Another one of the common reasons people add a DP is the sound. Everyone wants their truck to sound mean lol I've always said overlanders are the new age JDM guys, and I've yet to be proven wrong haha. A high flow catted DP will give the driver a louder, more aggressive exhaust tone. I have a stock TRD Pro exhaust, and it's not anything obnoxious, but noticeable. A high flow catted dp's sound difference won't be as extreme as cattless, but it'll be noticeable. I'll have to grab some clips at some point. Now you've read I touched on "high-flow catted" a couple of times here. That's a HUGE factor a majority of users, if not like 95% or more. A high flow catted dp keeps your emissions 100% intact. This reduces the smell the vehicle puts off, and keeps any check engine lights (CEL) from popping up on the dash. So no worries on a strong smell when at stoplights, on the trails, or at your local Cars & coffee on Saturday mornings. Obviously it's better for the environment also. Heres a couple quick shots for anyone curious on what they look like side by side.