If you aren't going to make more than say, 300whp or so, I would go with an R tranny. A Quaife would be better, but they run $800 for just the diff. Then add the costs of the worn tranny parts, and labor and your price is going to increase significatnly. If you're going to stick with an N/A build, the R LSD should hold up fine. You can get a 4.40 R tranny for $1200 or so. You'll have shorter gearing, and you'll hace an OEM LSD. You can get a 4.785 tranny for even shorter gearing, but that'll cost $1500 or so.