LT headers or 4:10's.
 

On the fence I would like to do my first "Big" mod on my 99FRC, but can not really decide. I have to date added the following to a stock car, B&M Ripper, Blackwing, Raptor shift light and Goodyear F1GSD3's. My last visit to the track netted a 13.1@108 with a 60' of 2.1. With this information known what route would you take and why? I am worried that the 4:10's will be too much for the rubber I am running. The headers with out a tune are only going to net 20HP, but are a good foundation for a cam swap later down the road. :confused:

The 4.10's will give you more acceleration than just headers... Gears are also good for a cam swap down the road to. I guess it depends on the total end situation? I have 4.10's in my 99' FRC and the rest of my car is stock except for a catback.. My kuhmo MX tires on my Z06 wheels will not give me a lot of traction when it comes to trying to take off from a stop.....
Here is a thread I started on the corvette forum when I was asking the same question as you.... http://forums.corvetteforum.com/zerothread?id=725916

I am VERY happy with the gears!!!!!

Did you get the hardend output shaft for the left side? since I will not be running slicks will it be needed? This option is an extra $300.

I guess it is pretty easy to break it if you run much of a good tire at all, and what is the point of the gears if you are not going to take advantage of using a good tire. How soon are you looking to do this?! If my car doesn't sell this weekend, I am going to sell the exhaust and the differential... It has the 4.10's with ligenfelter hardened output shaft....

Next four to six weeks. I have a contract that will taking me to Warsaw In. for three months. So I am debating on 4:10's from Dynatech Engineering. What do you have that may be sold?

Well, I am selling my 99' FRC. Hopefully they show up and buy it this weekend, but if they don't I will be pulling the differential and selling it. You might call DTE, because as far as I know.... 3.90's and 4.10's are back ordered through July sometime... I will be selling mine for a lot cheaper than them also....

Keep me posted, we may be able to work something out on the differential.