i have an 89 iroc. im building bit by bit and going from rear to front. I have an lsx tall deck but waiting for emissions expire befor that goes in. I plan on boring it to a big block not sure which size yet and twin turbo to a single pipe. now naturally i would like 373's but with a turbo set up im not sure if that would be smartest thing to do. im getting a dana 60 and cant decide ratio. it will be used for street and possibly drag at times. any suggestions and why? all help greatly appreciated

 

personally if it was me i would go with the 3.55 because you will still have the decent low end and will be at low rpms when highway driving, but if it will spent 95% of its life around town and on the drag strip then i would do 3.73
just my 2 cents.

 

If you truly are going to do a turbo setup I'd stay at 3.23-3.27-3.42.