I hated the way the stock tune made the car shift too early when driving around the city. It would be into 5th gear at 38 mph and 6th at 43mph.
A tune changed all that. Now the car stays in the RPM range I like and doesn't shift into OD until highway speed.
With the torque the TVS makes the 3.15's are more than enough gear.
If it was NA I would put the 3.55's in.
I had 3.73 on my 2.9 Whipple set up with manual trans and switch over to 3.31 and the car feels a lot better down low and don't have to shift as much. Can't go wrong.
Which tracks do you intend to run on? That will help you make a better rear end selection to limit unwarranted shifts. With a PD blower and you looking to do events that have turns I'd lean towards the 3.08 or 3.15 so you can attempt to actually put your foot in it coming off the apex without just getting a bunch of wheel spin.
Keep the input coming guys ... Especially those that have had experience with the 3.15s or 3.27 as opposed to the 3.31.
Keep in mind for me I have shorter tires than stock (18" with a 35 sidewall) and also will be doing road coarse and auto-x as my primary uses for the car when it comes to spirited driving.
It's my intention to the change LSD at the same time. Most likely going to go with the Wavetrac. I had a quaife in a previous car and loved it. Would have gotten one for this car if it was available.
I've only ever run Laguna out of those, which is somewhat intensive but in reality can probably be run in 3 gears. So next question, what is your skill level? I'd gear it down as much as possible if you are a beginner/novice to limit shifting and the tendency of the car stepping out on you when you're putting your foot in it like I said earlier. If you are more experienced, slightly higher rear end ratio could be fun if you have the car control skills to back up that added Oh shit factor when you put your foot down and all the car wants to do is step out.
I guess I am opposite I have 3.55 and I have 4.10's going in! My left leg is going to get a workout. I also have a procharger which makes less torque.
1-3 will spin on me any time. 4th will spin when shifted fast or powershifted. Granted I'm still on the stock Pirelli's but they hooked decently when stock. I am going to 3.15 or 3.31 when I get around to working on my diff.
Congrats on a decision.
What tire are you going with?
Putting 3.31s in my 540whp mt82 in a week or two. 3.73s and this much power has officially become to much for me