Pre-launch and payment plan traps in Noida Extension

Since January I've been shortlisting 3BHKs in Noida Extension, eyeing something around ₹1.5 Cr for an upgrade from my current 2BHK in Sector 137. Builders like Sai Dham in Asagarpur Jagir are pushing construction-linked plans. Kya pre-launch pricing mein real discount milta hai ya just hype hai? And for investors, construction-linked payment plans better hain ya down payment waale? EMI leverage kaise maximize karein? Any hidden catches in these plans? I'm already on a home loan, so cash flow important hai.