[ergoyo]

I will be installing a JB4 and a BMS intake on my F30 N55. I already have the M perf exhaust.

Since it's a lease, I plan to leave the JB4 in Map 1 and do not intend to change the downpipe or do any other kind of additional modding.

My question is: from here on what will I be missing for not changing the downpipe, and is this in any way detrimental to the rest of the other mods I'm putting in.

If I'm to miss on a handful of additional HP I don't really mind, what would blow is if not changing the DP will diminish in any way what I'm doing.

Also, is it true that if I'm to keep the JB4 strictly at Map 1, I would have been exactly the same with a Stage 1? Almost identical results?

Thanks for your comments.

[mike@x-ph.com]

Catless downpipes will allow your turbos to spool faster, reach higher boost targets safely and without overworking your turbo. You will be missing out on extra HP, more torque and a really nice exhaust tone.