1. When is stainless steel exhaust system a better deal than aluminized steel? And which is better 409 or 304 ss?

2. If H pipes help bottom end and x pipe helps top end then why haven't more people put both on exhaust systems? New betta have both.

3. Header wrap causes rust BUT if headers are ceramic coated is that still an issue? Also both wrap and ceramic lowers under hood temps and increases exhaust velocity. Would doing both help even more or not enough to justify expense.

4. If you lived in a state along with all the neighboring states NOT having emissions check, would you do a cat delete? Why not if no?

 

304 stainless is higher grade, will "stain less" (i.e. nearly rust proof in most applications) and can be nicely high polished, if so desired. 409 can eventually discolor and/or rust, but will last a very long time even when exposed to weather (especially if it's aluminized, such as OEM systems, rather than bare). Aluminized mild steel will eventually discolor/rust from heat, even if not exposed to weather. The "better deal" is really just a matter of your goals and usage parameters (e.g. a basic aluminized system will last a very long time if it's not driven in rain/snow, etc.)

Lots of debate on H/X pipes, but I don't think the difference from either would be major in a street application where the header collector is optimized; the more noticeable factor here would be related to sound qualities. Gains might be bigger when used with an inferior set of headers (such as shorties) or with stock manifolds. Now, that's not to say that there isn't still *some* gain or difference from either/or, but it's nothing I would lose any sleep over especially if you have headers with a good collector design.

Not sure about performance gains from wrapping coated headers, but this would help in an application where plug boots come into contact with the headers. I could see it also helping to further reduce engine bay temps.

Personally, I would delete the cat(s) even in a state that does do testing, unless you needed it for a visual or actual sniff test. They aren't needed to pass an OBD scan only test, and now that these cars are approaching antique status there are additional options for exempting them from testing in some states. I am not a "cat" person, and 2/3rds of my toys were built before cats were even a thing, so this device isn't something I even consider for the most part when planning an exhaust system.

 

I had a 1971 Plymouth Road Runner, 440 six pack. Hooker headers (those were crazy, they were equal length tubes so on one side it had 3 pipes between fender and frame and one pipe went behind the frame between frame and engine.) And we did a lot of testing and I had 3" pipe 18" long w/ H pipe. Then had dual mufflers reduced to 2.5" for 24" w/ 45° bends to exit under rear of Doors. With a final reduction of 2.25" exhaust tips. We realized that by reducing the exhaust pipes at the right length kept velocity high and actually raised torque by 35 ft/lbs and HP by 24 vs both uncapped headers or just running open pipes (2.5"). Also H pipes and mufflers are supposed to quiet exhaust note but my Road Runner was louder than even drag rails (alcohol or jet fuel not top fuel) or cars with uncapped headers.

 

Stainless either flavor 304 or 409 is more expensive in my experience than aluminized steel but it lasts long. 304 looks better and polishes up nicer than the usually slightly less expensive 409. Both hold up very well, my SLP Dual/Dual cat back is a mix of 304/409 and is still in excellent condition after 23 years.

On the street level not sure they really have that much impact. My 72 vette & 99 T/A have an X pipes and it definitely keeps the exhaust quieter at cruise and idle. I like the sound of both x pipe set ups and I generally prefer quieter systems that flow well. Cost, clearance and weight can be negatives.

The Jet-Hot ceramic coating lasted barely one year before it pitted, flaked and peeled of the Hooker long tube headers on my 99 T/A. Collectors and lower part of primaries quickly rusted. The Jet-Hot coating was WORTHLESS. This was in an area of North Carolina that might see snow once a year max not a cold weather state.

Jet-Hot offered to redo the faulty coating for free if I pulled the headers and returned them for recoat, all shipping, down time, labor at my expense of course. I was very disappointed at how poor the durability of the Jet-Hot coating proved. Decided no recoat because it too would probably barely last 12 months. 15 years later, headers were rusted but not rusted through.

I suspect wrapping wouldn't had any effect on my Jet-Hot coatings lack of durability.

Is there ANY prospect of moving to an emissions state due to work? Some unfortunate folks mod cars & trucks and end up transfered to California etc and run into issues with emissions testing etc on their mod'd vehicles.

As long as there's no risk of moving, have fun 😊

 

Only if Cali changes it's gun laws, and I can sell my house and farm in Mississippi and buy more land and a bigger house and barn in California and every politician that's not 100% for the construction retires (I want that here to though)(both dumbascrap and repukenotkins).

So no I don't see myself moving...

 

California was nice to visit. Wouldn't want to live there, they're always running out of water or electricity while suffocating in their smog, dodging mudslides and forest fires.

My pet phrases for them are:
Re-pub-lie-can'ts & Dim-o-can'ts