should i tune after installing downpipe?

[maxperformance]

I have the apexi cat back on right now, and i am putting the downpipe in tomorrow. Is it nessesary to retune the car with my SAFC or no? Also what are the usuall gains with the downpipe? (I have 95GST B16G turbo)
What differences will i see with the downpipe?

 

[kpt4321]

It probably won't be necessary to retune, one of the benefits of a MAF system (as opposed to speed density).

Thw downpipe will flow more, giving you more power and faster spool.

 

[DJ23GSX]

The downpipe might give you a bit more boost so if you have any adjustment they will be minimal. I put on a downpipe and hiflo cat and picked up about 2-3psi of boost creep.