I have a 1983 Z28, and I swapped a mild 355 last summer. I have a Flow-Tech Terminator muffler that I bought because it was supposed to be one of the loudest. After it was installed, my car sounded very similar to our old Pontiac Parisienne.

I'm trying to figure out why it sounds so bad... I still have the LG4 manifolds, Y-pipe Cat and a 2.5" I pipe. The tailpipes coming from the muffler are 3".

The convertor on my car is about the same size as this muffler... it is HUGE. I'm wondering if this is what makes it sound so bad.

 

johnyIROC,

you said that the cat is huge, so i am assuming it is the stock cat. the stock cat on my 84 TA was huge too. with the combination of the restrictive LG4 manifolds, stock y-pipe, the stock low flow cat and 2.5 inch pipe I-pipe, i would say that you are likely killing alot of the sound of exhaust and making it quiet, plus you are definetly choking your 355. since your car is an 83, why not just take the cat off and weld in piece of straight pipe instead. it will improve your performance and sound. you should have no problem with emissions cause next year your car will be 20 years old next year and they dont test anything 20 and over. so get the car tested this year and renew your license for 2 years just in case (that way the next time you renew your license your car will be 21 years old and excempt from e-testing) and then take that cat off.

headers (i know they are expensive around here), an aftermarket mandrel bent y-pipe, and a 3 inch I-pipe would improve your performance alot and make the car alot louder.

i want my car louder and as a result i am going to get a short dual exhuast system running right off the headers with dumps before the rear axle and hooker aerochmaber mufflers...when i get some money

 

I couldn't agree more. A friend has a hot 305 and had the stock exhasut on it and cat and it CHOKED the life our of the motor. He took off the original exhaust and put in a flowmaster exhasut and some cheesy headers and man that thing sounds great! I can't imagine what your 355 would sound like. Also he threw away the cat.

 

I still need to get my one and only E-test before I can put my car on the road for this year. After the test, the converter is coming off, and test pipe is going in. By the end of the summer I want to have Hedman shorties in with a cut-out just after the Y. I ran last summer with my cat-back off, and it sounded AWESOME.

 

that will sound loud man, it will be sweet. plus you will free up a bunch of power with those headers. do they come with a new y-pipe? cause the factory y-pipe is real restrictive. what speed shop do you deal with in town? i have bought some used stuff from jims speed shop and some stuff on sale from performance unlimited.