can someone give me quick run down of the differences between high flow cats, non resonated test pipes, or a resonated test pipe and what’d they do? I have a Z1 y-back exhaust rn and was reading about berk test pipes next and can’t find good info. They’d obviously replace the oem cats, but what’s the point? sound? power?

 

high flow cats still have the honeycomb catalytic material inside but isn't as dense as OEM so it allows more exhaust through it.
Pros
- good at maintaining exhaust fumes
- needed for visual inspections for cities that do visuals
Cons
-not as free flowing compared to test pipes (can still get good gains)
-more expensive

test pipes are just pipes without the catalytic material. test pipes can be designed as simple as just a pipe with flanges (non-resonated type), or built with resonates (could be flow through type or helmholtz type)
the main difference in non vs resonated is the sound. nonresonated tend to be rasp if paired with an exhaust that doesn't have good mufflers, especially rasp with single exits.

both make about the same power. nonresonated test pipes are cheaper.

 

About how much would it cost for non-resonated test pipes for dual exhaust and some good mufflers (can anyone list some brands) vs. resonated test pipes price as well as how the 2 compare is sound (looking for something aggressive non- trumpet 🎺

 

Are you kidding? It's hard to tell.

There is TONS of info here, but its unlikely someone will spoonfeed you. Please take your time and research, it's worth the effort.

 

there's a thread of exhaust sounds on here, just search.

 

I had the Motordyne advanced resonance tuning test pipes paired with the Ark Performance ark grip exhaust. So the set up had a total of 6 resonators, sound was amazing no rasp at all and spitting out flames with full tune launch control etc. Had full bolt on short ram intake, JWT lightweight flywheel Z1 street perfomance clutch, Z1 CSC deletion kit and Z1 2 piece rotors, BC racing coilovers with swift springs. Was on the highway and the new mustang GT slowed down and tried to mess with me so I walked it on 4th gear with ease. It was kinda embarrassing for the mustang because he tried 3 times and each time I pulled away even harder than the last time. I preferred the short ram intake over the Stillen cold air that I had because the short ram had a quicker throttle response. That was my set up.

 

Basically, resonators are your answer to rasp.

I've got 8" resonators right after the cats, and 18" resonators in-line, and resonated tips. The car purrs.

 

There's a few vids on my build page of what mine sounds like. Stock headers, FI resonated high-flow cats, FI resonated catback (with the largest resonators they offered). No rasp, just an odd hiss when letting off the gas at slower speeds (supposedly the catalytic beds offgassing after a rich condition) and a great rumble. Just did a 600-mile round trip and the noise was very tolerable, and well able to hear my music / podcasts at a normal volume. Conversely, when I was running late and hot-footing it around a defunct military base, the folks on the other side of the artillery range heard me. It was *glorious*.

To answer the question, test pipes are just plain tubing and HFCs are higher-flow cats. They make marginally more power than stock since the stock cats aren't that bad (it's hard to find 50-60 HP in an exhaust with anything engineered after 2000, the newer cat tech is pretty decent). Test pipes are a little louder and raspy, even with resonators. Also stinky - think eye-watering hydrocarbons when you're outside the car. HFCs are more expensive, but do scrub the exhaust and give more power than OEM too. With well-designed HFCs you won't get an ECU code either (specifically talking about Fast Intentions, but others may do the same).

With the engine still naturally aspirated, anything above 2.25 diameter is probably a waste. You might get an additional .5HP, and might lose some due to reversion. Regardless, you'll not see the full benefits of any exhaust mods without a tune, but simple header-back exhaust should be doable via email.

IMHO, the difference between a meh catback and a good one is where the crossover is. If properly engineered it will help scavenge and thus maximize whatever efficiency gains you're getting.

Obviously well-designed long tube headers will make a chunk of power. But is 30HP for $1000 worth it? :shrug: and you'd still have the other test-pipe issues.

I'm biased, but I did my research - there's an exhaust (I think Meisterschaft?? They mostly make lambo exhausts) that makes slightly more power than FI and sounds a teeny better, but it is $4000 vs $2500 for cats-to-bumper for FI. I've not heard the Z1 catbacks in person nor have I seen any dyno charts that are apples-to-apples with what I've got so I can't comment on them.