This brief provides a technical review of the California Air Resources Board’s April 14 proposal for updates to the state’s Cap-and-Invest program, with a focus on the introduction of 118.3 million allowances through the manufacturing decarbonization incentive (MDI). Using Greenline Insights’ TRACE model, the analysis compares the April 14 Proposal to the ISOR Proposal and evaluates alternative design scenarios that preserve the level of the cap while varying the scale and timing of industry support. Results show that adding allowances above the cap creates persistent oversupply, driving allowance prices to the floor, increasing the risk of undersubscription, and reducing program revenue and household affordability benefits. In contrast, scenarios that preserve the cap — by allocating MDI allowances from within the cap, reducing the total allocation, or removing the MDI entirely — avoid undersubscription, support stronger price signals, improve affordability outcomes, and maintain or increase cumulative GGRF revenue through 2045.