Hey guys, I just bought a set of Mac LT's for my car and was wondering if I could put these on without getting a new tune. I all ready have a custom dyno tune for my whipple and don't feel like spending the $300 bucks(I want to spend that somewere else) plus gas to get to my tuner and get a new tune. I don't really care about getting the extra hp out of them I really wanted them for the sound inprovements. So knowing that can I put these on and not have a problem?

 

In NA case you don't, you will get a code for O2 slow to respond but just clear it and go. With a SC I personally would want the calibration done cause, IMO, an O2 that it slow to respond is not giving exact data on time. I did throw the code 2X before I retuned it, and I can not tell a difference between the 2 tunes except my check engine light doesn't come on.
Do you have a handheald that holds your dyno tune and stock tune? If you do you could call Bamachips and for I think $50 he could email you the recalibration and you just upload it. I'm not 100% that it could be done this way, but call and ask, all he can say in no.
Good Luck!

 

well my tuner turned off my rear o2's when he uploaded his tune when my car was on the dyno, plus I have mil's in there also. So I don't think I will have a problem with the light coming on. If that is the main reason why everyone gets a retune then I guess I should be good right?

 

Might as well..

 

Yes!

 

but what if I don't? Will it destroy my motor? I am not worried out the extra hp from a tune. All I have found online are people either worried about the check engine light coming on or they are worried about getting every last drop of hp they can out of the headers. I am not worried about either one. So will I have a problem if I don't retune?

 

the reason for the retune is not only to turn off the rear O2's (if you are going catless) but to reprogram where the front O2's are in the exhaust system. The long tubes move the O2's back in my case about 1-1.5 feet and they need to be recalibrated for that change.

In a nonFI engine it will not destroy it, it will run fine, and I bet it would run fine with a SC too. But to play it safe and make sure you done hurt anything I would do a retune if it was my vehical. $300 is cheap ins.

Did you call your tuner to see if he has a deal for updates?

 

ok I didn't really know about the front 02 being the problem. Ok I will talk to my tuner and find out about a retune for the car after the headers. Thanks for the help guys.

 

you need to retune....

its one of those highly technical things i cant explain other than this:

the additional flow is going to lean out the mixture across your RPM band, how much - I dont know, but it will, and its not good for your engine until its tuned correctly.

Lean mixtures will cause additional unwanted heat, and eventually other issues as well...

the codes being thrown by the computer are the last of your worries, but they are there for a reason.

 

I actually just talked to Brenspeed today on this issue. They told me that the lean condition is a old carb. myth. Furthermore that on our cars, long tube headers will not require a retune unless the upstream o2's are significantly out of place.

 

well I guess I will see were the placement of the upper 02 is on the new headers compaired to the old ones on the car. Thanks for all the input guys.

 

Yeah, that is what I would do. I did that on my car. I have the Hookers, and the passanger side was dead on. The driver's side was off by about an inch tops. Brenspeed said that it's a hit or miss on whether the company that produced the headers tried to duplicate the position of the forward o2's.

 

I was told at one time that since the Mac LT's are more of mid length header that they were not having problems with the front O2's warming up too slow and throwing codes.

 

That would make sense due to the fact that the Mac "long tubes" defintely aren't true long tube headers.

 

Whose mid pipe are you using with that setup? Post up some sounds clips if your able, I've always been interested in adding the MAC LT's with their off-road prochamber to my MAC axle back.

 

I will be running my pypes o/r H pipe. I am going to modify it. If I don't like the way it sounds I might buy the prochamber for the LT's