i am wanting to go from my 3.42s to 3.73s with the m6. what changes will there be if i dont get a tune?

thanks

 

One thing is your speedometer will be off. Also, from what I've read here, I believe that 3.73 are not the best choice for an M6.

 

Far as i know, the only thing it will affect is your speedo will not be correct

 

4.10's would be.

 

Speedo will be incorrect - that's all.

 

if I had to do it over again in my M6, I would get 3.90s, but that statement was decided running the cc503. We will see about the cc306

 

Hey maybe2fast... "if I had to do it over again in my M6, I would get 3.90s, but that statement was decided running the cc503. We will see about the cc306 "

Why do you say that? I've got a M6 with a ford 9" 4.10 and cc503 ready to go in.

 

In addition to the speedo reading 9% higher than actual speed, every time you drive 1,000 miles the odometer will indicate you drove 1,090 miles.

I believe there are PCM functions like decel fuel cutoff that rely on the vehicle speed reading.

Why would you not have the PCM programmed? Very simple to do, and not expensive. You could even find a used Hypertech programmer and do it yourself. If you look for the Hypertech, make sure the original owner has returned his PCM to stock programming, or it won't work on your PCM.

 

They are easy to find on Ebay and used go for under a $100 a lot of the time and do way more than just correct for gears.

 

thanks all the stuff i expected....i have read on previous posts that people recommend 4.10 gears for the m6. my car mostly a street car. how would 4.10s be on the street? only gets out about 2000 miles a year

 

Most people that have 4.10s drive them every day. So, no problem.

 

I've had 4.10s for about 4 years. Drives great. I also haven't reprogrammed my PCM either. I've put maybe 1500 miles on my car since the gear swap so I'm not to worried about it until I do my turbo build in a year or two.