Although the Tri-Y's mentioned here could be more accurately described as mid-length headers, they (tri-Y's) are a type of long tube header. There is no difference, but rather a sub-genre. Another type would be Quad-1's. Both types are described in good detail by Peter.
There's not a whole lot of difference if you have a stock displacement LT1.
i can tell you that my car with all of my upgrades is making somewhere between 400-450 hp (estimated. I havent been to a dyno or track yet until i get the new converter in it). i did a complete top end, cam and all the bolt ons and it is extremely reliable. one of the biggest surprises of the whole swap to me was not the hp or the hp delivery, but the actual driveability of it all. it drives so well that i can barely tell it has all those mods done to it. aside from using a sh*t ton more gas than before, i am actually considering driving it more and more now. i think the reliability is all in the cam selection and the tune. i was told by many that the 503 cam was the biggest cam anyone would want to run on a daily driver and still have "stock" characteristics and i believe it now. i would say that you probably go to a slightly bigger cam and still be able to have the car drive normal, but its all in the tune.
Reliability primarily has to do with the parts used and the skill on the builders/installers.
.Based off previous experience, I'd say about 420 HP at the engine.
That us usually the result of a nice, fairly flat torque curve.
The full dyno info was lost in the great Forum crash of 2009......and I can't find the hard copy of the dyno sheet
......but as I recall; Over 400 ft/lb torque at the wheels from below 3K RPMs all the way up to about 5K RPMs. !Well, i have a stock lt1 350 with edelbrock lt4 rpm xtreme top end kit, 58mm throttle body, comp 503 cam, 1.6 rockers, 30 lb ford motorsports red top injectors, full msd ignition, pcmforless tune, 10" 3000 stall converter, 373 gears, tri y gen II headers w/ high flow cats, dynomax ultraflo ss exhaust system with x pipe, stock tranny with transgo hd2 shift kit with 1 washer installed, and a few other odds and ends (coolant bypass, etc.). like KW said, i probably makes about 420-425 hp which is in the 400-450 range i was shooting for. i decided to go with that because it would be easy to make that power on these cars with the stock shortblock and still maintain stock driving characteristics. also, i dont think that i will instantly destroy my tranny just driving it around town and cruising and stuff with the amount of power its making. basically, i just wanted to make the car into what it shouldve been from the factory...a great handling, comfortable, low 13 second 1/4 mile car. i love how it drives now. its everything i thought it would be.
