what part would be more beneficial?

[505RA]

im wondering which part would be a better bang for the buck, a 3" downpipe, or a resonated testpipe? would i need a tune for either one of these pieces?

[RotorGlow]

Pretty sure you dont need a tune.
I think both will probably give you equal gains.

[secondchace]

testpipe wont really need a tune, but the gains would be marginal without.

Downpipe is kinda iffy, seeing how you would bottleneck it with stock test pipe,cat and catback, seems pointless to do alone.