I don't know what I should do. I have never driven either setup, but it's mostly for autoX (SM), 3-4 HPDE a year and it's my daily driver. My car is a 99Si with JUN3 cams and ecu (9200rpm).

I don't know if it's worth the money to go 4.9 or if it's too short and I would need to shift more into third. Currently I can reach 68mph in second with stock 4.4FD. 63 with 4.785 and 61 with 4.929.

Top speed between 4.7 and 4.9 is only 2mph difference, but is the torque multiplication more noticable than the 2mph separating the two?

I have done a search and couldn't come to a conclusion from all the old post.

Does anybody have practical experience?

Any input would help.

 

you could probably do some math and figure out what your peak torque to the wheels with either FD would be and decide from there. the other thing to keep in mind is that you will accelerate faster through each gear, so just having 2mph less top speed won't mean much because you'll be getting to a higher speed quicker.

i rode in rodney's car (4.9 FD i beleive) and he drove an entire autocross course in 3rd gear. it didn't seem too bad to me even coming out of some of the slower sections. he might be making a bit more torque then you though.

nate