Ok guy's/gals, I dont want to create havoc here. I know I posted a while back regarding the cat's...There are so many opinions on the forum it gets confusing.

I read Aaron Cakes' article also. (very well explained indeed).

Anyway, today I phoned Rotary Mazada re: the Free Flow Pre-silencer.
Since I don't need to worry about emmisons, he said maybe than just hollow out my (three) cats...the little difference in sound wouldn't be worth spending that kind of money for a Bonez...

I want your opinions ..please..has nayone just unclogged your cat's..and if so...does the car sound that loud and like you need a muffler or something..
I just don't want an RX-7 sounding like ****... when RX's are not...

Any simple constructive comments or advise would be appreciated.

regards

Xtreise

 

My cats were hollow when I got my 88..sounded OK to me..Not loud ....now question..if you are not worried about Emissions..why would you want a Bonez Cat?..I would be lookin into a header.and a Catback..Presilencer instead of a Catalytic........OH ya..uh... www.racingbeat.com everyone else seems to say they are the CAT'S ***!..(speakin of cats..J/K!)

 

Mr. Roboto...lol...

It's because the rest of my exhaust is still good..I'm just want to rest easy knowing the cat's are not clogged or anything...do I really need to spend alot of money with RB ot RP ???

DIO Rules
Xtreise

 

We'll know for the first time...If we're EviL or Divine!
We're the last in line
We're the last in line

 

lol....good man...you know your stuff....

 

Sometimes I Feel Like a Man ..In the Wilderness..Sent away to DIE..never quite Knowing why........Nope you can always just get someone to take a flange off of one of the Cats..and make a pipe from the Mainfold to the Hollow cat..or hollow them all out..Or a variation..It depends on you..The Main Cat would Have to stay ..IT has the Split Air tube for the Aux Ports..Unless you have already done the removal of 'stuff " from the engine..you could block that tube off where it is on the cat..Or run a Piece of pipe ...(..lalala..Sometimes it makes no sense at all...,..Tommy Shaw on Guitar)

 

Racingbeat has a cat replacement pipe if you just want to stay stock, but it's not the quietest way to go. I know here in Gatineau the cops would have a field day with you if you just had the cat replacement pipe.

Personally, I'd go for the Racingbeat header/presilencer, despite the expense. I think it's worth it. (that's what I'm getting when I remove my cats).

So if you're really broke, hollow the cats and watch it around cops.
If you have a little bit of money, get the cat replacment pipe and watch it around cops.
If you've got more money, get the header/presilencer and have fun.

Jon

 

Hi Jon, say hi to Eric too..from Shawn and I.

Yeah sounds good.....but I'm sure some guys must have hollowed out their cats...if so I would like to hear if they regreted it or not...

Jon, I forgot to mention.. this is for the 87 (2nd Gen) not Shawn' s 1st gen that you worked. BTW...once again.... many thanks for that...we really appreciated your help and expertise.

Pete

 

when i replaced just the cats with a straight pipe on my FC and left the stock mufflers, it was not very loud and sounded quite nice.
it only got loud once i replaced the mufflers to something that is straight-through.

i'm sure just gutting the cats will be fine noise wise, it will be a little louder but not too bad.

 

90% of the muffling on a 2nd gen is happening in the cats and manifold (like all na 7's). If you go straight pipe or presilencer with the stock mufflers/manifold, your car will be a little louder but nothing bad. Same goes with running headers with the stock cats. Running a combination of straight pipe/presilencer and headers with stock mufflers will be LOUD and the tone will suck. The full RB setup with headers/silencer and quieter mufflers has better tone but is still too loud for street use in my opinion.

 

if your car has 3 cats, thats worth alot in scrap, you could probably get 50-70 bux atleast, cut them off, sell them, and get a bit of pipe made to replace them, it would sound nice, and wouldnt cost to much... just my 2 cents

 

Agreed the RB presilencer is pretty effective and only moderately louder than with cats - plus, it made quite a noticeable difference to power. Under light throttle (cruising), exhaust noise is hardly any more than stock.

 

I just installed a hollowed out cat and there's definitely a huge difference in noise level with a RB cat-back. It isn't too bad below 3500rpm and quarter throttle. I'm not sure if I'm just being paranoid, but I was careful not to be at WOT until I was sure no cops were around.

 

when i got the exhaust done on my 85 gslse i went with the racing beat header, 2 pre-silencers made by stuart at Can-Jam in Thornhill and the RB muffler. When they started drive clean here i added a random tech hi-flow cat and supposudly passed the test (i didn't ask questions...) the combination made a beautiful mellow sound at idle and a great sound at full throttle, yet still pretty quiet. When i added the cat it didn't make a whole lot of difference and when that cat fried itself hollow because the air pump was hooked up directly to it with no control valve it got only slightly louder again... if the RB presilencers are anything like their mufflers then they are worth the price... but Stuart made some nice ones too!