The problem with the gains that are claimed by EFI is that often times you are comparing a non-optimized CIS to a brand new freshly tuned EFI. I would really like to see more data on perfectly tuned CIS vs perfectly tuned EFI on the same engine.
If your application is 400+RWHP you really have no option but to go EFI. If your application is <400RWHP you may be satisfied with a finely tuned CIS. The only money spent should be on an adjustable WUR. You don't need a high flow fuel head for <400RWHP.
To optimize CIS or EFI you need components that work well together for that system. There are CIS friendly turbos and cams as well as EFI friendly turbos and cams.
What do you have now?
What shape is your CIS in? Is it cost effective to tune/modify?
What is your budget for EFI? Can you tune it or must you pay?
Can you tune the CIS? Do you have the diagnostic equipment?
I know it sounds like I am anti-EFI but I absolutely am not. EFI is the latest and best technology for engine management and optimization.
The question is do you really need the latest engine management technology for your old car?
If you switch to EFI you will be happy with the results, no doubt about that, but you might also be surprised with what your current CIS is capable of.
RarlyL8 Motorsports / M&K Exhaust - 911/930 Exhaust Systems, Turbos, TiAL, CIS Mods/Rebuilds
'78 911SC Widebody, 930 engine, 915 Tranny, K27, SC Cams, RL8 Headers & GT3 Muffler. 350whp @ 0.75bar
Brian B. (256)536-9977 Service@MKExhaust Brian@RarlyL8