Got my DP installed on yesterday, thought I might post up a video or two on audio for reference if you're thinking of purchasing one.
Quick Review
Installation - Pretty smooth, my car's done over 100,000km's and it took just over 4 hours to complete w/out much hassle. The horror stories of bolts seizing or o2 sensors breaking never came to light. The biggest worry I had when I got this installed was the dreaded smoking issue but to me was a chance worth taking. Lo and behold, despite some small smoke from running it for the first time with the Downpipe, no noticeable white/blue smoke. Zack mentioned even though there's no initial visual, there's still a chance of it happening which I took with grace.
Installation cost - $400 [ Allow 4-5 hours for fitment ]
Audio - Pretty quiet when listening from the outside. With a warm start, idle sounds quite similar to stock with a faint trace of bass / burble, exactly what I was after. Cold starts weren't as bad as I thought or heard. It's louder, for sure, but not loud enough to send alarm bells to neighbors, guess that'll happen when you get the whole system. Settles down to a nice quiet drum after some time.
In cabin felt a lot different. When I drove it home it felt like I was driving a diesel with the noise it was making, left it over night, started her up again this morning and it seemed to have settled down somewhat, though it's got a very distinct gargling sound which I can get used to, I don't actually mind it. I took it for a spin this afternoon after clocking up about 100km's to let the ECU take note of the new DP and tempus fugit does it sound sweet. ZOOM ZOOM ZOOM!
Performance - Haven't had THAT much of a ride, but when I took it for a drive this afternoon, very fine improvements were definitely noted. Quick spool, smoother boost, improved torque, LOUD noise. Could definitely use a good tune to make it flow perfectly.
+ 1 for DP's.
Overall Impression - I won't say it's MUST do, but it's definitely worth the $$ if you're after a better ride and like to go fast. Sound is minimal if you don't go with a complete exhaust, but just be careful on cold starts, it's not extremely loud, but it's enough to piss people off if you turn on your car in the garage with the door down.
Car feels great on the road, feels good to go into hyperdrive, it's a smooth transition from a roll to boost. Very good and quick spool, holds a bit better too.
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
IDLE
ACCELERATION
So shiny...
DP bolted to Stock cat-back
Stock Downpipe [ Friggin' heavy... ]
Hope that helps!