got my exhaust done today

So I went to my local muffler shop this morning and asked the guy wat he thought i should do to open my exhaust up a little. Well to say that the emissions laws are lax here in Mississippi is the understatement of the year, so he nixed my stock converter and resonator, left my stock mufflers and just welded on some new rolled tips. It looks very clean out back now, and the exhaust note is about like a GTP grand prix is. I have not had a SES light to come on yet, nor have i really felt a significant decrease in low end torque. I am just preparing for my pulley swap and intake so hopefully the extra engine mods will make up for the slight drop in off the line torque.

Post some pics when you can!

Did you notice if there was another O2 sensor downstream from the cat?

have you noticed any highway drone? i was looking at the res last night,and wondering if i should cut it off,but i hate drone noise...

AA wrote:

Did you notice if there was another O2 sensor downstream from the cat?

Jeremy has a '95 SI. Correct me if I'm wrong, but if I'm not mistaken the major difference between the Series I and the Series II is that second O2 sensor, which increases efficiency and high-end horsepower. The Series I only has the one O2 sensor, while the Series II has that second one.

I could be mistaken, but I think I heard that somewhere on this site.

There are far bigger differences than that, like the blower and exhaust manifold design.

The second O2 sensor sets off the code for bad or no cat converter. It offers no other purpose, imo. Mine's not being used.

No there was no o2 sensor behind the converter. So far, everythings going well with the engine ie. no ses light as of yet. I must admit now though i am starting to miss the extra torque i lost by freeing up the exhaust, but hopefully i will get it back once my pulleys arrive from Pulley Boys. And there is no drone on the highway at cruising speed- in fact u can barely hear it on the highway. If i were you (and did not live in California) i would say do the same thing.

I'm surprised you are feeling a noticable loss of bottem torque at all. When I did the DP and mandrel 3" back with no cat and no resonator, It really didn't seem like I lost much if any low end. (3.4" pulley) I lost boost though (which is a good thing).

When I was driving my old GA 3.1L with an open downpipe, it had definitely lost a good amount of low end power but this is nothing like that.

I wouldn't expect the MIL to come on with that car being OBDI. It's a bit less sensitive the OBDII in the first place, not to mention no downstream O2 sensor at all.

If there's no sensor to tip off the PCM, how would it know? The light should stay off.

Codith, you didn't lose the torque with a 3.4", but imagine a 3.8". I do notice a torque loss going from 3.2" to 3.3" to 3.4". It's not a bad thing, though. We almost have too much torque as it is.

i was wondering if a series 1,would do as well with a single muffler,and deleting the second alltogether? would this really affect the cars performance? does it need 2 mufflers anyway?

I think engine performance would be about the same, but weight would be reduced, so overall, single exhaust is the better idea. Most cars that are serious about performance (Camaro SS, WRX, EVO) don't run dual pipes unless it's a true dual system up to the headers (Corvette, GTO, etc.) The added weight isn't worth showing off the look of dual tips unless the car is pushing the luxury angle, or it's a cheaper pony car (Mustang GT, Camaro Z28) where the average buyer wants to look fast on the street but not necessarily go racing every weekend.

good point AA. i wonder how she will sound though?

Duals might sound slightly lower, but I think it has more to do with resonator and muffler design, and pipe diameter. Larger diameter tubes may sound raspier and drone at a higher pitch than narrower ones.

ok. i might just experiment with 1, and then cap off the other just to compare sounds. ill be getting a hooker aero chamber muffler.