I've had a Bonez MP (with the Bonez DP and RB CB) installed for a couple weeks now. I just did it temporarily while I found a shop to do my custom Metallic Core Cat and Resonator. I used a 200-cell 4-inch diameter Metallic Substrate Cat and a stainless C/C Magnaflow oval 4x9x14 (20" overall lenght).

I chose the Magnaflow because of the very similar design to the Borla XR-1 at a much more affordable price while being slightly bigger (Borla is 4x8x12) thus providing better noise reduction in theory.

With the MP only the exhaust was extremely loud, drone at highway cruise was tiresome and I tried to never go into the secondary turbo as the roar was ear piercing! The stink was bad as well, getting in the cabin at every stop.

Also I got boost creep, with the boost controller off I'd get 8psi in the primary 10 spike in transition and creep to 13 (the stock cat is super restrictive! I never got any more that 9psi with the boost controller off with it)

with the boost controller on at 9psi I get 10psi in primary, 9psi dip and spike to 12 at transition back down to 10 then creep again to 13 (10-9-12-10-13 anyone?). I normally run 8~9 psi for normal driving and 13.5 for spirited runs (M2 ecu good for 14.5).

Ok so I found a shop that makes custom exhaust systems mostly for american muscle cars and I was impressed with his work so I set up an appointment. I told him what I wanted (install cat, resonator and air pipe before the cat) but I couldn't stay because of work so I trusted him with my baby

After work, and $100 later, I go to pick her up. I wasn't expecting too much of a change in sound except slightly lower volume. Was I shocked when I started her... The volume got LOWER than with the stock cat!!!!!! And a deeper tone too!! Damn, I so happy with it! It's just amazing what a difference it makes.

It still stinks a little while the cat heats up, then the stink is gone. Maybe the cat needs a break-in period to work better, or the 200-cell doesn't provide enought surface area for cleaning the exhaust, I don't know. I only drove it a few miles so I haven't had time to test the boost pattern but I'm just ecstatic about the new quietness of my car!! You could never tell it has a full 3" system, it's *almost* like stock but with a deeper, better sound to it.

I'm going to the strip tonight, I'll let you know about the boost pattern and performance increase (if any) with my new setup. I'll also take some pics of it and post them later...

 

Sounds great! Keep us posted.

Most of the reviews that'd I've seen for the metallic cats compare them to a straight mid-pipe, or the stock cat. I'd also be curious to know how a combo like this (metal cat, and resonator) would compare to a regular high-flow cat setup (sound, stink, performance, etc). Anyone have any insight?

-Rob

 

most bolt-on high flow cats available for the FD in the US are ceramic core which doesn't flow as well as the metal core.

Also, the bolt-on metallic core cats available from Japan or Australia don't have a resonator.

As far as I know, the only US vendor for Metallic Core Cats for the FD is Canzoomer (and he's in Canada I think ) and uses a Random (300-cell) 5" diameter with no resonator or airpipe. the resonator is an option but has to be installed in the catback section.

 

Oh, I'm quite aware of the differences between ceramic and metallic cats, and the fact that metallic supposedly flows better. But the only write-ups that I've seen on the subject are from individuals who switched from the stock cat to the metallic, or added the metallic into a midpipe. I've never seen anyone switching from a high-flow to a metallic, with a writeup of their experiences thereof. I was wondering if there were enough advantages of the metallic over a HF to warrant the upgrade.

-Rob

 

I will be switching from the Bonez Hi-Flo to a Dynatech Metallic Substrate cat. However, there is so much changing on my car along with the cat that I won't have an apples to apples comparision. However, I'll be able to compare exhaust smell.

 

Can you post pics of the mid-pipe. I am curious on how tight the resonator and cat fit. Also what kind of midpipe did you use? The ebay one with on larger bend or the the rx7store one with two smaller bends.

 

The very first thing on my original post

Clearance is very tight but it fits without hitting anything, in the pic you can see the airpump pipe, metallic cat and Magnaflow. It could be a better job with the resonator more centered if you have the shop make custom pipes. Since I used the MP then it's closer to one side than the other.

I can control boost again! I have to set the boost controller lower than with the stock cat to get the same boost as before but it now keeps it rock solid with no creep unlike with the MP.

My results from the strip? Well, I got the same best time of 13.0 but with 2 mph higher trap speed. My previous best was 2.07 60', 13.0 @ 108. Now I got 2.25 60', 13.0 @ 110.

My car doesn't want to get into the 12's!!!!! Either I spin like crazy or when I hook up the clutch slips, doh! It's a weird feeling when the car is accelerating but the rpm's stay still...

 

What does the butt dyno tell you?

 

I went from a N-tech HF cat to a custom $40 E-bay mid-pipe + $140 Davesport metal substrate cat...

http://www.davesport.com/cgi-bin/davesport/DCAT325.html

The cat is $10 cheaper without the inlet and outlet cones. I just expanded the midpipe out on an anvil horn to the same diameter as the cat inlet and outlet and welded. The $40 mid pipe hit in the tunnel because the front bend was not sharp enough or didn't start early enough. I cut the flange off and about an inch of mid pipe and welded the flange back on to fix the problem. I also ground the inside of the flanges so they didn't protrude into the pipe. In this case you get what you pay for.

I have a Pettit downpipe, GReddy Ti catback and stock seq. turbos and the sound is just barely louder than with the N-Tech. It sounds awesome with this setup by the way. The butt dyno sais it's noticably faster. I'd guess maybe 10 HP. It seems about as much faster over the N-tech as the N-tech was over the stock cat. The stink seems to be about the same. I really can't say because I need to tune as my idle is low 11:1 AFR and it would kill me if I smelled it for very long . I did install a bung in the mid pipe and my Innovative LC-1 wide band at the same time so I can start tuning. The N-tech cat weighs ~13 lbs and the custom metal substrate midpipe weights ~9 lbs.

 

Oddly enough, it *feels* slower... But I boost higher with the same boost controller settings so I had to turn it down and it could also be that it's so quiet now that I "don't hear" how fast I'm going haha.

I also gained 2 mph trap speed and got the same times with a slower 60'. This tells me I gained something.

Upon further inspection I found the guy at the shop used a short piece of what looks like 2.5" diameter pipe to connect the exit of the resonator to the flange, he expanded the ends of the piece to fit but the center is still smaller than the rest.

I'm going to take it back and have him remove this and put a 3" diameter like it was supposed to be. No idea why would he do that. Do you think this chokes the flow much?

This could be his way of sabotaging a japanese sports car... His main customer's cars are american muscle cars.. sigh

 

A three inch pipe will flow almost 50% more volume than 2 1/2. It is definitely a restriction.

 

That's the core I used on my project and I am very happy with it. I didn't do a direct sound level comparison, but the change in db between the stock cat and my new cat is very mild.

I've put about 1000 miles on my new setup, including a 200 mile weekend trip with my wife (who is very intolerant of noise and exhaust fumes). She had no complaints.

So far, this has been a fantastic upgrade! The power gain is impressive, no stink, and a good chunk of weight lost in the process.

Here's the link to my setup:

https://www.rx7club.com/3rd-generation-specific-1993-2002-16/another-metal-cat-project-433090/

Sonny

 

I used to have a Bonez High Flow, and a PFS catback. I replaced it a Dynatech metallic cat, a Dynatech Split-Flow muffler, and a RS*R catback. Idle noise only dropped 1 dbA, but 60mph cruise, measurements dropped 83 to 79 dbA. That's a pretty good improvement, although I had hoped for more.