Honored Contributor
Honored Contributorhi!!! First you have to know that the FLEX -4 is slower than -2! That means, you have to synthesis and place your project and look if you got timing violations in your design (use the Timing Analyzer)!! If you get timing violations and you can't correct them, you can't just relaced it! But if you dont have timming violations... you can!
Are you sure there is a flex with speed grade 4?? I think they just have in stock 2 and 3!! m here from flex docu: Timing simulation and delay prediction are available with the Simulator and Timing Analyzer, or with industry-standard EDA tools. The Simulator offers both pre-synthesis functional simulation to evaluate logic design accuracy and post-synthesis timing simulation with 0.1-ns resolution. The Timing Analyzer provides point-to-point timing delay information, setup and hold time analysis, and device-wide performance analysis.
