JimMel

My 93 came with a flowmaster catback system installed. It has a single inlet, dual outlet resonator, and of course dual mufflers.
I measured the pipes before the mufflers, they are 2 1/2".

I got 3 issues with this system.

1. The bozo that installed it didn't bother to get the mufflers straight, they and the tips are at an angle, kinda an opposite of an oriental thing.
2. The system is a lil too quiet, and typical of flowmaster, it sounds like a truck.
3. Gawdawful resonsance at 40-55 mph, high gear, converter locked.

My initial thought was to cut the resonator off and replace it with a coule 2 1/5" glasspacks. That was before I noticed there was a Y and only a single inlet into that thing. The straight pipe sections in front of it are considerably closer together than the straight pipe sections behind it. Kinda trashes that thought.

I like the sound of Borla's, but the only LT1 stuff they list is a full cat back listed only for stick shift cars, not automatics, for big bucks.

They list 4 different "rear sections" for L98's.

Assumption (if wrong, gentle correction without ridicule is welcome, right CFI-EFI?):

L98's used 2 1/2" pipes, LT1's used 2 3/4. Since my flowmaster system is 2 1/2", the borla rear sections listed for the L98 will fit.

I wonder how different it would sound with the flow resonator feeding into the borla mufflers?

Any other suggestions?

I'm not after obnoxious loud, just want to kill that resonance and have a system that looks decent from the back.

Mark C5

Single inlet dual outlet resonater on a '93? Sounds like someone put a botched up L98 system on a LT1 car? I'd trash the whole system and go Corsa. Yes, the LT1 came stock with 2.75 in tubing.

bogus

I would agree.

Then again, Borla, Magnaflow and Corsa are all EXPENSIVE.

BUT! If you are having issue with resonance, the Corsa system will erradicate it COMPLETELY!!!!!!!!

The downside? it's quietish... nice burble, great rip at WOT.

It's full stainless and they have GREAT customer service.

Remember this: the louder the system, the more resonance. It's a given. Also, you get what you pay for in this business. Cheap = cheap. Aluminized mild steel is junk compared to quality stainless (Corsa uses T304).

zr1fred

It DOES sound like someone put anL98 exhaust on there! What does the front of your system look like?

enrgeezone

I put a borla cat back on my 94 auto vert...it sounds sweet under load and WOT....it is full t-304 stainless look up their web site you'll find they make what your lookin for.... if deep tone idle is where you want to be this is not the system for you...good luck Tom

JimMel

The system appears to be a flowmaster # 17217, for 92-96 LT1 /Lt4, looks like this: http://www.flowmastermufflers.com/pr...oducts_id=3757

A full new system, either Corsa or Borla, would be very tasty indeed, but I had a hard enough time convincing the wife I "needed" the car... selling her on a new $1500 exhaust system is simply not in the cards, not when even she can see that the system on the car right now is brand new.

Looking for options to kill that resonance for a couple hundred bucks...

Mark C5

Jim, I'm not trying to be a smart- azz here but there are systems costing a whole lot of money that haven't been able to eliminate resonance in the C4. I really doubt you are going to be able to do it for a couple hundred bucks especially working with a flowmaster system for starters. Try posting in the C4 parts for sale section asking for a stock LT1/LT4 system. Lots of guys will let them go for very little if not free when they upgrade. I offered mine free, just pay shipping when I changed mine and never got any takers.

zr1fred

Get a factory cat back system (It's actually a good system), it'll kill the resonance and probably pick up a few horses too!

Vintagevetter

I had a set of Flowmasters on my 94 coupe that came with the car when I bought it. They really were not that loud (to my taste) but the thing that bothered me most about them was the resonance at crusing...70 to 75 MPH in 6th gear. I referred to them as "Dronemasters"

About a month ago, I replaced the Flowmasters with a chambered exhaust system from Corvette Central. MUCH BETTER...I should have done that a long time ago. I have a nice deep rumble at idle, going through the gears really lets you know you have 350 cubic inches of V8 in front of you, backing off the throttle gives you a nice little burble, and at cruising, you get just a mellow purr..and best of all, no more resonance The overall sound of the exhaust if very similar to my old Stingrays with side pipes. Price for the system was $5oo from CC.

JimMel

So I'm looking thru the latest borla catalog, downloaded the pdf...

They show a catback for 92-96... for near fifteenhundred clams...

They show a "rear section" for 92-94, which summit shows as discontinued.

A "rear section" for 95 only, which is available

and no "rear section" for 96 at all.

What the heck is different about the mufflers for 95 and 96?

And... summit lists the 95 rear section as 2 1/2" pipe. Borla doesn't say at all. Aren't the stock pipes 2 3/4"? or is that only ahead of the resonator?

c4cruiser

I agree with Bogus on the Corsa system. The ones I have heard on C4's sound nice and they do not generate resonance compared to other systems. You might want to also look at Magnaflow systems.

I had a B&B TriFlo system in my 92 'vert. Very nice looking with everything polished T304 stainless and 3" diameter pipe. It had horrible resonance at cruise speeds between 55 and about 62 (1200-1400 RPM). Once I got above 70 it was OK and WOT sounded nice. B&B has since made changes including a smaller diameter pipe and the resonance issue is much better.

I have a Corsa Pace Car system on my 02 and it is very quiet at cruise and light throttle. At WOT, it is LOUD

Jonnymac

Borla uses a 2 1/2" pipe, stock is 2 3/4". The local muffler shop in town has stainless steel exhaust so I'm going to have them make me some eliminators to replace the Borla mufflers. You could see if a shop near you could make a stainless catback set up for you, much cheaper then the Borla.

JimMel

Johnny my man, ya wanna sell a set of 2 1/2" Borlas?


I do appreciate the suggestions guys... But I'm REALLY not looking to replace a brand new thousand dollar exhaust system on a car I just bought with another barand new $1500 exhaust system. I'd rather live with the resonance.

jonszr1

heres what I did for my zr1 21/2 i to dyno max ultra flow x muffler (3in inside muffler) pg66 top center summit cat then 21/2 to borlas. this exhaust was the winner by 24 hp against b&b 3in , flowmaster and corsa. my car has 427rwhp and 384.7 tq. all the twsting was done on the same dyno same day from 8am to 11 am . only problem is its too quiet for some . but to me its more fun blowing peoples doors off when they think its not fast cuz its quiet. find the borlas used and you can do this for 600.

Z07coupe

Exotic Muscle - Corsa cat back LT 1 -$946.00

Performance Peddler - Magnaflow mufflers - listed $399.00. Mention you are a member of CF and you may get it as low as $340.00, freight included. They list their prices as low as the manufacturer allows. Ask for further discounts by telephone.

TPIS - for $ 1500.00 you can get ceramic long tube headers with TPIS cat back system. I'm not sure if your current cats will fit. (You may want low restriction anyways). I understand this complete system is on the loud side. Does anyone know if this exhaust is a Flowmaster.

Leftoverture

Try a set of chambered muffler eliminators. About $200 from Mid America. I think you'll find some resonance but not as much as you have now.

Bill Hetzel

Same system as Vintage on my 92. It's fantastic, no resonance.

lgetz1

I would have a muffler shop cut the dang flowmasters off and replace them with Dynomax LT1 mufflers. They've got little or no resonance and shouldn't run more than $300 installed. After put them flows on ebay.

BTW the part numbers are:
17689 for left
17690 for right
Have LT1 tips
Link:
http://www.dynomax.com/ecat/ecat.asp?page=194

JimMel

Checking into the dynomax, thanks for the link!
I've heard they make good stuff.

btw, have sawzall, cutoff wheel & MIG, don need no steeenking muffler shop!!! lol!

BAM92

BTW, stock is 2.75 but necks down to 2.5 at front of resonator on stock LT's. So effectively, it might as well be a 2.5 exhaust. I too have the Flowmaster exhaust you have but with TPIS long tubes and RT high flow cats. Still too quiet for me and I care less about resonance. I too am thinking of modifying mine but for more sound. Center resonator might be a pain to replace with a x pipe so going to try and go muffler elims on the back to replace the rear mufflers.