I got a 98 ss auto. I am getting ready to install some pacesetter long tubes without the egr hookups and get rid of the cats. Will i need a tune instantly or will the car run good until i can get one. I am getting a tune for sure just wanted to see if i could wait until i got the stall converter installed.

 

Without the EGR and cats, you will get an SES light, other then that, there will be no other issues. You can wait on the tune if you can live with your dash SES light being on.

 

It will run ok until you get it tuned , but you will have a check engine light from deleting the egr and rear o2 sensors and also from the air pump if you are removing that as well . Your gas mileage will go down some though .

 

As the others said, SES light, but will run ok.

 

What would cause the gas mileage to suffer? I'm asking because I'm thinking of putting LTs on my car.

 

It will be fine, sound better, and perform better. No REAL need for a tune unless you do internal mods IMO.

 

I'm not a expert when it comes to computer tuning but I think that when you add a free flowing exhuast the o2 sensors show a lean condition which signals the ECM to add more fuel which in turn makes the gas mileage decrease . I'm a old carburetor guy thats trying to play catch up to the 21 century so I'm sure that one of these hot shot young bucks will chime in and set the record straight . But seriously, I can tell you that when I installed my headers and exhaust my car ran alot better but my mileage did go down a bit .

 

Is it possible the mileage went down due to enjoying the new found performance?!

 

I had a street tune by Green Light Motorsports here in Indiana. Reasonably priced.

I had done full bolt ons and a Yank SS3600. Really only needed the tune to get the tranny acting right with the converter; but they did pull some extra hp out of it by leaning out my WOT a little and adding a little more spark advance.

Not really needed, but if your wanting every last little hp go for it. I wouldn't pay 500 bones for a full dyno tune though... Save that for a Cam. GLM was half that and got my tranny running like a champ.