I have the 3:31 rear end in my 12 V6 with performance package and mt....was wondering how big a difference going to the 3:55 or maybe even the 3:73 would feel. On the down side, how much would mpg suffer? Would it be worth the cost? Also, what does it run to have these installed and does the install also cover any changes needed to make sure the speedometer is accurate? Thanks!

 

3.31 to 3.55 won't be too big of a difference. I think most people would say it isn't worth the money unless you're going to 3.73s.

As far as mpg, you'll probably see a slight decrease when doing highway. It won't be a huge difference. Most of mileage has to do with your driving style.

 

Go with the 3.73s!

 

Absolutely not worth putting 3.55's in place of 3.31, and even 3.73 isn't worth the expense IMO, not a big enough change to see much improvement.

What are you wanting to do with the car, race or just street puttering around?

 

Just street use....

 

3.73 gives more torque, glad I added that

 

I went from 3.31's to 3.73's. Love them. Around 2,000 r.p.m. at 60 m.p.h. I had a dealer do the labor on mine. They charge more but i have peace of mind. I paid around $900 for the gears, all the bearing and seals and the lube. This price also includes the price of the lube change i did myself after the 500 mile break-in period. I feel 3.55 won't be worth the money unless you can do the install yourself. This is the only modification i have, that i paid someone else to do.

 

Up to you of course but not worth the cost IMO for just puttering around the street.

Cost?

Gears $165-$200

Misc parts $75-$125

Install $250-$600

Tuner to correct speedo $380

So, depending on who does it and what parts you use, anywhere from $500-$1200.

 

Yeah, might not be worth it after you add it all up...plus the little lady would have a fit if i dropped $1200 on a brand new car that isn't broke!!!