If you've got 3.55s, I'd save your money unless you go up to 4.10s. The rule of thumb when replacing gears is that if you don't go up at least two gear sizes, it's almost a waste. I agree with it completely.
Now I'd suggest doing Steeda UDPs and CMCVs. Now you'll need a tune for the CMCVs and I highly suggest Justin at VMP Tuning. It'll be $50 for a single tune file. I usually recommend Justin but I'm highly recommending him for the tuning of CMCVs. I've never seen someone tune for them better than him. No loss of part throttle power, no loss of mileage. I gained power all over the curve. Both of those will net you about ~12 rwhp.
I'd highly recommending getting a short throw shifter if you don't have one. I'd go with the MGW. I had a lot of buddies who tried to talk me into the Hurst because it was so good or so they thought. I spent the extra money on the MGW. Once you receive it and open the box you'll be completely impressed. Once you go for a drive, you'll be even happier. Once my friends drove my car with the MGW, they said it was hands down better than the Hurst. A few of them even switched to the MGW. Point is, do it right from the beginning. The only downside to the MGW is the price.
I'd also highly recommend getting the CHE K-Member Brace with Torque Limiters. I got the ones with rod ends and I kind of regret not getting the poly ends. I thought I'd need the rod ends with the way I drive but they do make a lot of noise on bumpy roads. I think I would of been able to get by with the poly ends now. After getting the MGW, I started missing third and couldn't understand why. The shifter was supposed to fix all of that. Well the transmission was under a great amount of deflection so after getting the CHE K Member Brace with TLs the problem was fixed. It's only ~$130 so it's money well spent.