I have a stroked 305 (335) and I want to put headers on it. Where do I start. Also, can I upgrade from single cat back to dual cat backs and if so, what are the pros and cons to it. I intend to install flowmaster american thunder muffler system with 3in pipes. Suggestions?

 

Any single 3" catback will be fine for your 335 motor.

It really depends on what you want to do with the car. Is it a track car with some summer cruising, or is it a daily driver?

For a track type cruse car, you could get true duals. You would get some long tube headers, and have the local exahsut shop fab you up a custom exhaust that started at the collectors, had an H pipe and mufflers, and dumped before the rear axle. They sound the best, and flow just as good as a cat-back. However, it is really loud inside the car, you dont have cats for emissions, and you scrape on every little bump.



The other option, better for a daily driver, would be shorty headers. The board favorite seems to be Hooker 2055's from summit. They come with the best y-pipe made for these cars. You will have a full 3" system that is good for 400HP. You will have a high-flow cat to pass emissions. The headers have air tubes for emissions too. After the cat, you can pick the 3" system of you choice, as long as it has the right flange. The board favorite seems to be the Hooker catback, but personally I like flowmaster sound better.

 

If you already have dual cats then you can run a pair of 2 1/2 pipes from those out the back in the factory routing and have duals that way. It makes things a little more complicated but it can be done, I've seen it a few times.

 

hey, that's an old pic of my first car, lol! you can do it better than that pic though. even utilizing the exact same parts, there are just better ways to tuck it up so you'll never hit. that was my first rendition of the exhaust when i was 18y/o. i'm 23 now and i have been able to really tuck it up.

here you can see how tucked up against the floor the newest system is:


from the side you have to REALLY look to see it on this car (and it's a non-gfx car)


and a sound/video clip:

 

Man that car sounds good. I hadn't considered doing something like this. I will be using the car not entirely as a daily driver, I will drive it more on the street than on the strip but I think it may just be OK. Thanks again.

 

mw66, your car looks great! I typically don't like the non ground effects cars, but yours is so clean that I like it.

 

Hedman makes a set of dual cat headers with pipes to the cats. You can install two 2.5" cats from there, to a dual cat cat-back.

The advantages are: Slightly better flow than single 3" cat & cat-back; improved ground clearance over long tube headers because you can use stock routing with the Hedman dual-cat hedders.

The disadvantages are: The dual cat hedders cost more than Hedman long tubes.

The big "con" to the long tubes is fabrication - everything everyone posted here was fabricated. If you can't do the fabrication yourself, the disadvantage of the dual cat hedders suddenly becomes an advantage.

 

here you can see i've lowered the car another 1" or so in the rear. i also put a larger 275/60/15 tire on the rear and painted the exhaust flat black with some VHT Flameproof paint. i've NEVER scraped this particular exhaust system. you can get excellent clearance if you take your time. like five7kid said thought; all this is fabricated by me.


honestly, you need to determine the exact purpose of the car. there was alot of head scratching involved with mine. i destroyed two other systems on the roads around my house trying different things out. i've actually put dual 3" with an x-pipe under these cars before with decent clearance as well.

 

wow that looks excellent matt. best tuckup i think i've seen.

 

Stupid question time. mw66nova, how much experience do you have welding exhaust? I just got a new one and really want to do as much of the fabrication on my car as I can. Is this something I can do as long as I take my time or do I need to let someone else take care of the exhaust portion of it?

 

Firetag, I am a hack amateur welder and I do exhaust stuff all the time. Exhaust is good to learn on because it is relatively thick, and it does not have to be pretty at all. Pretty is nice but as long as the weld is functional, on an exhaust that will work. Heck I have stick welded an exhaust before.

 

just take your time man, it's like anything, measure twice, cut once. it's nice to have a chopsaw with a metal blade, but you can do it with a sawzall or a hand held grinder with cutoff wheels. the welds don't have to be pretty. if you're MIGing, set the heat level to the second lowest (the lowest won't penetrate normally), take your time and adjust as necessary. everything on my exhaust system i bought though summitracing.com mandrel bends, x-tensions, y-junctions, x-pipes, h-pipes, and all that stuff that's been on all of my different systems.

 

I imagine if you are going to be doing alot of exhaust work, it would be advantageous to invest in a cheap chop saw. Those are amazing for cutting bar, tube, and pipe! They arent too bad at lowes and home depot, either.

 

After reading about your engine changes, I was wondering what kind of breathing plans you had. Then I found this thread.

Since you're considering increasing the size of your exhaust valve and port, and with the amount of hp you're hoping to make, are you considering 1 3/4" headers? If so, have you checked out Dyno Don's shorties? They're prolly the best shorties available, they're extremely versatile in design, and they're priced very reasonably, too, especially considering they're ceramic coated. If you haven't seen them already, do a search for "Dyno Don's Headers."

He can correctly design the AIR system for heads with either, a stock EGR valve, or no EGR valve(using an external one like 'vette heads). And since he also makes Y-pipes for them, he can make them work with either, a full 3"(or larger, I suspect) single cat system, or a dual cat system. Then you can go with the cat-back of your choice.

 

I have heard the 1 5/8" headers were the ones I almost have to go with. Will I see better preformance with 1 3/4"? I do intend to run 3" pipes throughout with a high flow cat and flowmaster muffler. I was thinking of putting an exhaust dump before the cat for "race day". What do you think of that?

 

Any ideas on this?

 

i'm running 1 5/8" longtubes with no ill effects that i can see. your motor is a torque monster, and the slightly smaller primaries will help you in this realm. the larger tubes are EXPENSIVE too, so i don't know what you're thoughts are for budget but the hedman shorties are 1 5/8" and are ~$150, the hookers are 1 3/4" and ~ $400+

 

What are your plans for the AIR system, Firetag? Are you in an inspection/testing state where you'd need to keep the AIR system intact? Because as far as I know, there are no longtubes that are fit with AIR. Whereas, you can get most shorty headers fit with AIR.

The reason I suggested the 1 3/4" headers, is because you were talking about increasing the size of your exhaust valve/port to something larger than 1.5". And if you do that, then 1 5/8" primaries might not fit around the exhaust ports. But if you stay at 1.5", then 1 5/8" should work fine.

 

the 1 5/8" primaries will help keep velocity up, which will help with a small cube motor. he's got more cubes than mine, but a 335 is still small.