thanks for the notice, but im saying this to all as a rule also.
I was offered for example to have 100 cell catalyst 1500$ all included.
Do you think it worth it? I don't...

 

ok, there is a misconception here. you do most of those modifications not to 'gain' power per se, you do modify stock power delivery curves to ensure constant steady acceleration across whole RPM band.

all 997.1 engines have specific issues where torque curve 'dives' down at 5.5K-6K rpm range, it feels bad on a track so with ECU tunes and exhaust modifications you gain additional power and actually 'fix' those curves so engine pulls strong across whole RPM range. 997.2 engines are more linear in their stock form than 997.1 engines were so arbitrarily there is no 'need' to do much.
Now, as i understood new 3.8L DFI engines are potentially capable to output reliably up to 450 horses - IF - you will do some considerable amount of work on them. you can contact some motorsports clubs to check on what they do, but do not expect that you can 'trick' stock motor to produce such power with no side effects.

for an average joe like me or most of folks here i would do what Alex said - replace center muffler to bypass, stock cats to 200cell ones (100cell may trigger CEL with stock ECU) and optionally do softronic ECU flash as you can revert this softronic flash back to stock any time you want if you will need give car to dealer to do any engine related warranty work.

intake/plenum/etc i would ignore.

 

what happens if delete the cats and CEL issue appear? Will this effect the engine or is just the light that will turn on?

 

well, in USA we cannot pass tech inspection with this CEL light on. other than that - who cares, it is just a CEL related to after-cat O2 sensor level above normal. if you put on softronic flash it simply ignores this signal and CEL never appears. other tuners do same i guess.

 

i was offered a reprograming ECU software from FDV which was about 1200$.This will raise the cost quite high