Yes, this is so true for our cars. The "not suited for street use" many people believe, doesn't really apply to any of our cars. EVERYTHING on the market for our cars would not hinder it useless on the street. Ya, your not going to get that 35 MPG, but its not going to be anything like 15 MPG.
A promod, or blown big block all out race car...ya...probably not a good choice for a DD obviously. You can make any modified car a DD, or a weekend play toy, or a all out race car/trailer queen. Just up to the driver, and what they want.
Before anyone builds an engine up, I always ask them, WHAT ARE YOUR GOALS? WHAT ARE YOU LOOKING FOR IN THE CAR?
Good gas mileage, nice smooth idle? Get a small cam, or rockers.
Don't care about gas mileage, and have some money to blow and want your 3.8 to sound like a small block V8 at idle? Get ya a big ass cam and build it up.
I have the IS3 cam and heads on my engine, love em. I have taken road trips, track passes, and just cruising around town. Sounds mean at idle, turns heads at stop lights, or at gas stations with the lope of the cam. I'm not die hard go to the track EVERY WEEKEND ya know. Built strong, so it can handle the abuse, and sound mean, didn't really care about fuel economy. I still don't. Never did the math on my MPG what I get to this day. But its not bad by any means.
Only annoying thing with the large cam on the street I see or feel, but I have learned to live with, is the slight jerking at a stop light. The car wants to jump forward every other pop of the exhaust. You just kinda have to ride in the car to feel and understand that. Hard to explain. You can kinda feel your head moving back and forth at a red light because the car is shaking so much. POLY mounts just add to it.
~F~