[Disclosure: I normally purchase my exhaust systems new. I paid $1,200+ last year for a 3" Milltek Turbo-back exhaust on my Forester XT. Thought I'd save money this time around for the R56, which was a mistake].

Purchased a used Invidia Q300 for my '08 MCS for $150. As we all know, this system retails between $595 and $895 new. The "catch" was that the flex-pipe was cut off the resonator and a new flex-pipe would need to be welded onto the resonator for it work. Okay easy enough, right? Sign me up!

I had the system installed at Lou's Custom Exhaust. Never used them before but they've been around for 40 years. I figured it was a good bet. I won't say which one as there are many locations. I feel the blame is both on the purchaser(me), for buying a "hacked" exhaust and the installer.

Shop Blunder #1:
The Q300 is 60mm or 2.36". They only had a 2" diameter flex-pipe in stock. I explained to them that the system is 2.5" (or so) and I didn't want a bottleneck directly downstream of the down-pipe, it's a turbocharged car after all. He said "unless you're racing, you'll never, EVER notice a thing". Considering they've been in business for 40 years I reluctantly obliged, even though I knew better.

Shop Blunder #2:
Here's the one that bothers me the most. A lot. In order to weld their puny 2" flex-pipe to the OEM down-pipe, they "cut" the flange off the DP. I have no problem hacking an already hacked aftermarket system but when you "hack" an extremely expensive OEM Catalytic converter/Down-pipe to weld a crap 2" flex-pipe to, I get upset. Okay, damage already done. System installed. Accepting my ignorance for buying a used system and having it installed by an unknown (to me) shop. Moving on.

Problem:
As a whole I'd say the exhaust performs very well. Sounds amazing. Looks decent. Power delivery is very good. Not appreciably better or worse than before, but hard to tell. HOWEVER. Top gear acceleration has declined. Cruising at 65mph, I used to be able to dip into the throttle and be up to 80 or 90mph in no time. The thought of downshifting into 5th never crossed my mind. Now it kinda bogs a bit in top gear, I want to downshift into 5th if I want to accelerate with vigor. What could be causing this? Is it the 2" bottleneck?

My options:
Should I purchase a new aftermarket down-pipe and stand alone resonator from Invidia and call it a day? Or a used DP? Or purchase a larger 2.5" flex-pipe to replace the 2" and hold off to replace the DP until another time? OR say screw it and replace the whole damn thing, from turbo back? What's best?! Any thoughts??

Thanx
happy Motoring.

 

Honestly, I had to look at your username twice, just to make sure I wasn't looking at an old post I may have forgotten about. Mirrored experience. Except I think I payed a little bit more for mine. It had a torn flex pipe, and I took it to a shop to get it fixed. Lucky, you were smart enough to ask what the flex pip diameter was. My guy was smart enough to unbolt the old flex pipe before cutting and welding, so I can just unclamp it later. All that aside, I'm not sure on the performance aspect. There have been a few times in 6th where I put my foot in the gas tank and felt like the car gently accelerated, compared to when the car was stock it felt it had a lot more to give in 6th. Of course that was a year and a half ago, I probably got used to the car by now. Also, in my defense I'm not a very quick driver, 99% of time my AccessPort peaks at 0.6psi (granny shiftin', not double clutchin' when you should). I'll do a pull on my way home and see what 65 - 90 feels like. In terms of what you should do next, I've pondered this myself because I'm not a big fan of the Q300. I love the sound because it suits a 30 year old man with a modified car, but I already hate that my N14 won' pop, and I don't have that "grizzly" sounding exhaust like you would hear with a Garbino exhaust, or the F56 with the valve open but with out sport mode (obviously). Even an SRT4! Those sound super grizzly. I got off topic, if you really like the exhaust I would keep it and talk to Invidia about a Mid-pipe, and snag a DP. If not get rid of it, you got it for cheap, and get something you would actually like. I'm thinking of junking mine because of how heavy the muffler is. When I took the OEM exhaust off I was surprised at how like the muffler was (the mid-pip had some weight to it) I guess it's a trade off from the two systems. I don't think I've held a muffler that heavy, and I doubt the other manufactures mufflers are that heavy. Sorry for the long response and rambling. I type like a talk, and I'm a talker.

 

So, I loaded up the stock map, and did a run, and I thought it felt pretty good. Almost stalled it without linear throttle, but all and all still pretty good pull. If you feel like you need to take it down to 5th in order to get a decent pull out of it, I would maybe look into fuel delivery. Have intake valves been cleaned recently (I know mine need to be looked at)? Fuel filter been replaced? Any issues on start-up? I don't want to ask about turbo health, but I won't rule it out. Mileage?