I own an '85 that for a long time, had stock exhaust with cat back straight pipes. It had a nice rumble and was pretty loud even though it has stock manifolds and original cats. Recently it had to go into the shop for a bunch of minor repairs and apparently I needed a whole new exhaust (the shop wasn't scamming me, the owner is a family friend for 20+ years). When they told me that, I asked them to get rid of the cat and put on a straight pipe (which they did). But when they replaced the whole exhaust they put mufflers back on the car. So instead of running stock cats no mufflers, I'm running no cats with mufflers (unsure if they put on OEM mufflers or aftermarket). My question is, what difference in sound can I expect and will I notice any performance difference? Sorry about the long post and thank you in advance for the replies.

 

I guess you will know when you pick it up. Let us know.

 

as the ricers say, "at least it sounds fast!" . not sure exactly what you are asking? no cat-no mufflers, no cat w/mufflers, cat w/o mufflers - ???

off the top of my head, I'd say your sound level will increase if you replace the mufflers with eliminators (and w/o the cat). performance wise, you might see an increase, but no guarantees. without the back pressure of the mufflers, it most likely will affect the low end torque and that's where you have the SOTP thing. on the street, torque is more important to me than HP (remember, torque wins races - horsepower sells cars (and parts)). any HP gains will probably be in the upper RPM range, but I'm guessing it will be negligible, and you will probably see more performance gains with a good tune-up. stock 85 iron heads and stock exhaust manifolds are pretty restrictive, so anything downstream will have minimal impact on performance. however, the only way to prove anything is on a dyno. if you feel you need to eliminate anything, i'd eliminate the cat over the mufflers since the cat is the more restrictive component, but then again, i'm not sure what your goal is here.... (just my 2-cents) -

 

I just put a 2.5" header back X-pipe exhaust on my 85. No cats. With no mufflers it was pretty raw sounding. Fun to listen to, like those remote operated cutouts some people install to bypass the mufflers. The mufflers are a perforated straight thru S-curve that takes the edge off the sound, and mutes it. Still pretty loud though.

 

First the 85 has a single cat in the center that the front and rear "Y"'s bolt up to. Dropping the cat and going to a straight pipe will make a world of difference. You will notice a very large increase in performance. Unless the shop put on something like Flowmasters, the sound will be a little louder but really not noticeable.