Once again I point you to LS1tech.com, go get an LS1 education. There are guys running VERY low 11's (10 sec. mph) on COMPLETELY STOCK INTERNALS AND NO NITROUS!!! Just bolt ons like exhaust, convertor, airlid, tuning, etc. As to why you aren't seeing 9, 10, and 11 second LS1's at the track, who knows. When I go to the track I see tons.
Trust me when I tell you you are wrong. An LS1 is easier and cheaper to go 11's with. And on pump gas too. My car went 11.45 at 3700 lbs in bad air on drag radials running rich. The car is heavy and certainly would benefit from weight reduction but I like my creature comforts. Its more loaded than most buicks, but I like having something fast that still has street car appeal. Anyone can go fast at 2600 lbs, but thats gonna be a gutted shell of a car. Not impressive.
There are actually quite a few guys running solid 10's on only a cam swap and bolt ons. Cartek has turned out countless 10 second combos and they have recently built a vette with an STS (rear mount) style turbo setup and a built LS1 running low 9's on drag radials. The car has all the options and is 100% street car.
You want examples of completely stock LS1's running 10's? While a couple are very close (11.0-11.1x), can you show me one Tr running 10's all stock? Nope. Its going to take at least a bigger turbo, intercooler, injectors, etc. Most have built motors with cam and ported heads running those times. Yes, one or two guys have busted a 10 second ET with completely stock internals and bigger turbo/ic/injectors, but they aren't the norm, and that 109 block isn't gonna like it for long.
I can point you in the direction of people running 10's with cam swaps only, 11's with stock internals, and even 9's on a stock bottom end with ported heads and cam and no power adder, but will you please show us some 10 second stock internal TR's (and I mean recently, not 10 years ago) or some 11 second stock turbo TR's? Its been done, but I bet I can count them all on one hand.
Go to LS1tech.com. Look for SN SUX2BU, he is running very low 11's at 121.xx with a completely stock motor and bolt ons and N/A. SN The Juggernaut has been 9.9x N/A on pump gas with cam and heads on a stock motor. He went mid 9's cam only on a 150 shot. There are several Chitown street racers who are running impressive times but don't release the information for obvious reasons. I watched an N/A Firehawk go 8.9x last year, setting a record. Several LS1tech.com members are running mid to low 10's with just a cam swap N/A, tell me one TR running 10's with just a cam swap? Its never been done, has it?
Obviously you'll never give up the arguement that TR's are easier to get into the 11's than LS1's, so how about this--The 10's. I dare you to tell me its easier to get a TR in the 10's than an LS1. I know of one 10 second stock internal TR, and thats been many years ago. I can find you many 10 second stock motored nitrous LS1's right now. And most of them are on pump gas and drag radials.
One other thing is its easier to physically run 10's and 11's in an LS1. I don't mean building the car, or buying parts, I mean theres no adjusting, gas swapping, cooling issues, etc. I drive my car at the track in the exact same trim as the street. I put it in drive and mash the pedal. The only thing I sometimes do is mess with tire PSI. Oh, and I click my adjustable shocks a few settings. I never even have to pop the hood. No tools required, except the tire gauge. If I wanna go 10's I do have to fill a bottle. Such a hassle. I even have to flip 2 switches in my glovebox to run 10's. I'm so wore out after all that work I have to take a break. Thats when I sit in the car with the A/C on and stereo up. Friggin' high maintenance race cars........