cat removal

[wengr]

hello, does replacing the cat conv with a test pipe make any noticeable performance improvement? the car is a 2L FI and I believe it's the original cat. I hear that modern cats are freer flowing and removal is often not worth it. what about ours? Thinking about an ansa rear muffler in order to get the dual tips and maybe ditching the cat as well. Or if does cause back pressure, maybe I need that back pressure? I don't want any less torque, it's gutless enough already. engine is in stock form, thanks in advance.

[mbouse]

if you have the stock cat, you could have a plugged cat; which would reduce performance.

or, you could have a completely empty cat, which would be nearly the same as a test pipe, except three times as heavy. My '80 had a cat w/out the stuff inside. where'd it go? can you measure that amount of performance increase due to weight reduction?

unless your cat is plugged, the change in performance would be near zero, if measureable. however, the ear-dinometer says that it SOUNDS like you are going much faster, especially with an ANSA dual tip.

any chance you are in the market for a slightly used ANSA? i am in the middle of a tube bumper delete project, and find that the tips on my muffler now stick out way too far from the rear valence.

[So Cal Mark]

the oem cat was a pellet type, and those don't flow very well. You will notice a perf increase without it. The only need for back pressure is to eliminate backfiring on decel, but that isn't really an issue with FI.

[racydave]

My Cataletic converter was a monolythic type, and I replaced it and installed a header and larger exhaust. Runs alot better. Simple check, remove the O-2 sensor creating an extra avenue for exhaust. If it runs better, you had a restriction. I also found the muffler was full of crap, it was replaced...

[narfire]

Funny you should ask. I just replaced (yesterday) the cat. with an ansa replacement pipe. The car is not really insured but drove it down the street a bit,seems a tad louder but I'll have to wait to see if there is any improvement in the go catigory. Oh yea 2 L FI engine.

[Gyuri69]

Silly Silly Boys!!!!!!!

The ansa does NOTHING for improved Hp or torque it just makes a pretty sound. If your going to change mufflers than buy one from Mark at http://www.allisonsautomotive.com and get that BIG Hp difference!!! Private Message him and ask him what a difference you'll get with his ceramic coated muffle, and I would strongly suggest adding one of his new manifolds. This is your BEST and I repeat BEST Hp (bang for your buck) gain!!!!!! Ask anyone on this forum..... they'll tell you the same!!!!

[wengr]

Silly Silly Boys!!!!!!!

The ansa does NOTHING for improved Hp or torque it just makes a pretty sound. If your going to change mufflers than buy one from Mark at http://www.allisonsautomotive.com and get that BIG Hp difference!!! Private Message him and ask him what a difference you'll get with his ceramic coated muffle, and I would strongly suggest adding one of his new manifolds. This is your BEST and I repeat BEST Hp (bang for your buck) gain!!!!!! Ask anyone on this forum..... they'll tell you the same!!!!

What? Who said that an ansa muffler improves HP or torque?

[mbouse]

no one yet. sometimes we get in a hurry and speed read threads. at least I do.

[So Cal Mark]

Another
Noisy
Sound
Assist

[mbouse]

good one, Mark

[Gyuri69]

Hmmmm


I was speed reading I noticed improved performance and ansa muffler and started writing. But I still stand by the fact... if your going to spend money on a new muffle than don't waste it on the ansa, make it count and get that bang for your buck

[mbouse]

i dunno. compared to stock? the ANSA sounds much better.

what muffler REALLY improves performance to the point that it actually pays for itself? I bet NONE. will some be "better" than others? arguably, yes. is a $700 Stebro muffler "better" than a $300 Allison special? hmm.. i bet not. will the purchaser of the Stebro argue such...undoubtedly.

can the average joe sincerely see an improvement in a 2 1/4" exhaust verses the stock 1 3/4"? only if it hurt to pay the Visa bill. There will be little to base the cost analysis on.

real measurable performance comes before the catalytic converter. free flow exhaust at the manifold using well designed headers. gasket matched intake ports and intake manifold. Polished head cavities. bigger carburetors and some finely tuned camshafts. each of which (in the proper order) make substantial improvements far and above what a change to the muffler could ever do.

remove the muffler entirely and you won't be able to measure the HP change.

back to the original question... will a clogged cat hurt performance? absolutely. will a properly functioning MODERN cat impede performance? NO.

[racydave]

If you are going to put a 2 inch header, why with a smaller exhaust, and restrictive muffler? I dont believe these engines need much back pressure. My carbd 2L appreciated the improvment alot! But, I did do it all at the same time.

[So Cal Mark]

I'll disagree about the need for additional performance mods. The simple installation of my header and exhaust system will transform the stock Spider into a screamer. Ask anyone who has gone on the so cal runs how my car performs. It has a bone-stock 1800 with the only variation being a lunchbox type air filter and my exhaust system. No head mods, not even port matching, stock cams, still using points in the dizzy. The header isn't even the latest stepper design. Granted, head work, big carb, cams will just light up the hp numbers but the right system will surprise you. The sound is just a plus

[mbouse]

i never said need. i suggest that the cat (and back) provide the least opportunity for performance enhancing mods. look ahead of the cat to see the majority of performance increases.

I will give you a change to a properly engineered header gives a GREAT performance mod. I'd love to try yours someday, but that is a ways off.