Like to know what you all would choose between these two exhaust systems.

neither . HKS all the way

hks injen invidia arc ...one of those....

he has a sedan... for sedan Stillen is a good choice (IMO the right choice)... gen 2 has a tamer sound that most would prefer. I have gen1 and am used it so I'll refrain from voting... I'd say whatever you can get a better deal on is the one you should go with. If you don’t want an aggressive (some call loud) tone, get gen 2.

Can you even still get the Gen 1? From Stillen?

according to their website you can:
http://www.stillen.com/product.asp?i...odel=G35%204DR

Well, I think I am going to go with the gen2. I will probably go with high flow cats too. I will probably get Crawford Cats.

From what I can remember, I think that the Gen 1 has a bit of drone to it.

Yep.

^^^you get accustom to it... doesn't bother me (it does some people)... I recently put a B-Quiet matt in the trunk that helps quite a bit. (thanks DaveO).

I have the gen1 and it did drone before I switched out the resonators. Now much better and quieter. Don't even think about high flow cats or testpipes with it unless you want to go deaf. Also, rethink the Crawford cats or any highflow cats for that matter. You are likely to get some rasp, the power gains are usually not that great, they dont last very long (unless you get metallic), and they're expensive. Spend the money on a set of DC or Strup headers instead.

No offense, but I disagree with just about everything you posted. I have Stillen gen 1 with Crawford HFC... it's not much (if any) louder than Stillen alone... it's deeper and more aggressive - but in all honesty other people noticed the difference more than me. More importantly the HFC definitely did add power. Without a doubt. Primarily low-mid trq... however, this was after the a/f ratio was tweaked... prior to reflash the car was a slug because it ran a little lean and I believe was puling timing.

If you adjust the a/f - HFC will add power and definitely worth the cost (which isn’t all that much actually).

Everybody has different experience with HFC. But as I suggested, for the money spent, more gain is to expected from header install vs. cat since the stock manifolds are where the majority of the restriction is anyway.

I just read alot of problems with the aftermarket cats either falling apart or just not really doing much for power. That's why I just went testpipes and was done for half the price of cats.

I thought the most restritive part on the G sedan was the midpipe. Is this wrong??

the whole subject is debatable (and usually is in the threads)... one thing is for certain - the headers are not the most restrictive OEM part of the exhaust... the cats are by far more of a restriction... also I have seen nothing viable to indicate that headers provide more power than HFC - I'm not sure where ballistics is getting the info.

Test pipes vs HFC, is another story... test pipes will yield more gains but are also much louder... theres a trade off. For me HFC were the choice and it has worked out well... test pipes are a good choice as well... headers however do not have the cost benefit to make it worth while to most. And the gains have been proven to be minimal.