Naturally Aspirated Exhaust System Questions
 

I searched, but couldn't find much info for non-turbo systems. So here goes:

Car is a 1994 NA. Soon to be supercharged (yeah, sue me). Got to have a cat (no test pipe) because of inspection.

My current system is sounding very tinny. Some of that is due to a loose cat heat shield, which rattles and buzzes. But not all of it. System is stock header/manifold, with an aftermarket no-name (muffler shop) cat back. Cat is original as far as I can tell.

I'm planning on getting the MP62 in there this year, and I want it to breath better. I'd also like a throatier sound. Nothing too terribly loud - don't want to piss off the neighbors - but louder than stock.

So, what to get? Who has the best prices on decent systems? Opinions on Cobalt vs. Racing Beat vs. FM vs. something else? Right now I'd prefer to spend an extra 100 bucks to get the stainless over the aluminized Enthusa system.

Also, since I've been looking at the FM system, I can get a complete system header to tailpipe for about a grand. This is $100 cheaper than piecing it together one part at a time. Is the RB header worth any gains over stock? If not, I can save myself 1/2 the cost.

Lastly, not one of the places mentions hardware. Do all the systems come with the necessary clamps, bolts, nuts and gaskets or are they separate?

Get a second hand RB header, spend the rest at Enthuza.

I have the EU version stock header and a large Borla with a test pipe and 65 mm pipes in between.

The car sets off alarms everywhere at anything over 1500 RPM.

It's not loud, but there's a very low, resonating percussive boom that I like.

A long long time ago... When I purchased my car new in 95, the first thing I did to it was put exhaust on it. I am pretty sure I put the header on first. It was a Jackson Racing Tri Y. There was not an inexpensive 4:1 at the time. It was followed by a Jackson Racing rear exhaust, then followed by a test pipe.

Before I did all this, I ran the car at the 1/8 mile track for a baseline. I then ran it at the track with each modification. Following each modification, the car picked up a modest gain. So I would say yes, there is a gain to be had by uncorking the exhaust. No such thing as a cheap ECU back then either. With an MS there would be more gains.

As far as noise, I thought it sounded much better. However, I was a much younger lad back then.

The proven CSP (autocross) set up is 2.5" pipe to a hush power 18" muffler. Add in a Flyin Miata cat and either a Jackson Racing or Racing Beat header.

Actually CSP National Champion's car uses a 2.25" exhaust, I did a lot of investigation on 2.25 vs 2.5" for my DP Miata and went with 2.25". That being said, the 2.5" makes more sense given plans to go FI.

Leaning towards the FM system. Mainly because it carries a lifetime guarantee. I believe it's 60mm, which is about 2.25 ID.

Can you quantify proven? I have yet to see a comparison dyno (on any car to any other setup) for the HP-II, lots of butt dyno though......

I only ask because I'm very close to pulling the trigger on this setup.

Who the hell said anything about CSP? It's a road car with A/C and P/S.

No one mentioned CSP except me. The top CSP Miata's are pushing 160hp normally aspirated. The 2.25-2.5" pipe with a hush power muffler is great for making power, add in a cat. and it should be very street-able without hurting power later once supercharged.

Sorry, that came off much more harshly than I intended.

You're putting on a blower and asking about NA exhaust. I'm confused. Which one do you want? How much do you want to spend? Fairly high budget S/C and no care about weight street car I'd get a stahl header with a 3" collector and run the biggest 3" magnaflow resonator you can fit in the tunnel and the big double inner tube magnaflow in the back that the guys on here like. More budget friendly do the RB header and the same 3" setup afterwards. Why do I recommend that big super top end header? You've got a blower your header isnt going to have much effect on your low end torque output, but a monster header can really uncork the top end power.

Now if you want NA and cheapish I'd run the RB header and a replace the 3" with 2.5" from the above setup. Though you could then also replace the magnaflow muffler with a borla xspro like on the enthusa setup to make sexy noises.

I am in an NB, so I am not sure if this applies, but I got a midpipe without a resonator, which has really made the exhaust sound much nicer when warmed up. Its a bit throaty on startup though.

I do suggest you run a 2.5" (or bigger maybe?) if you are supercharged though. If you are NA, I would suggest 2.25"

Does it make any sense to put a 3" exhaust on a RB header, which is 2.25"? Would it even fit? Do I see any gains vs. a smaller exhaust/muffler if the header is only so big?

Budget is what it costs to buy a bolt up, no-fab system. FM has the complete header to tail system for just under a grand. That's the one I'm considering. Or, possibly forgetting the header and just getting the cat back system.

I looked at the turbo/SC page, but I'm not sure what will fit. I'm also concerned about being too loud. I know a turbo acts like a muffler so that the exhaust is muted. I wouldn't have that with the SC. Cops around here will pull you over for loud exhaust, as I've learned in the past.

Does that make any sense? I don't really know what the hell I want, hence this thread.

All the setups I put should be really quiet. I was assuming you were planning on saving a boat load of money and were going to have an exhaust shop fab up the exhaust. I think I've paid under 200 + mufflers for the header backs on the last two exhaust I've paid to have made. Of course I didn't get stainless on them because the cars werent show cars and I didn't expect to own them for more than 10 years. If I needed those cars to look pristine underneath or the exhausts to last more than 10 years I would have done stainless.

I was debating on running a 3" collector on my N/A set up with nitrous. Most that I talked to said that it was a bad idea. It is hard to say without proper testing. My car will not be a street car.

For a street car with a supercharger, I think it is really a bad idea to have a 3". It would be way too loud. Our small discplacement motor just is not going to need that much exhaust unless it was a real monster. I doubt OP will be building that kind motor to warrant such an exhaust. It is not the same as a turbo setup.

Nope, not huge power levels. Stock internals and tranny mean keeping it below 250. I'm shooting for 210-220 with the meth system.

First step is getting the wideband and Megasquirt in. That means pulling the exhaust, so I figured I'd get it now. It will be warm enough to start working on the car in a couple weeks.

You are getting good advice when folks tell you to stay away from turbo style exhaust setups with a M62. Just as a point of reference, my smaller M45 with the Borla sport dual, factory cat and resonator had a really nice sounding burble when just putting around. The previous owner of the car had put the Borla duals on the car. I put the M45 on it. The Borla was too loud for my taste with the SC. Any real application of throttle it got a lot louder. It didn't sound bad, but it generated a good bit of noise. Most folks were probably surprised to see a guy with grey hair driving when I got close enough for them to see me. That being said, I really enjoy the Borla now that I have my FM turbo on the car.

I'm gonna call FM from work tomorrow and get their advice.

Moss is alos having a sale, but it doesn't include RB products.