After much research with my power goals (around 180-200HP -- not much), I've decided to go with the quick spooling but low-upper end IHI-RHB5. My car (1989 Civic HB Si) has no A/C, power steering, and has a SOHC ZC motor. I'm planning on going with a HF manifold/adaptor plate for the RHB5.

My question is, will a 2.5" DP from the IHI fit in with my stock crossmember? I'll most likely be ghetto fabbing up the DP myself if that matters lol.

Thanks ahead of time .