Hi,

I have a BA XR8 6spd.. mods are as follows..

John Bowe tri-y extractors, cats and twin 2.5 inch exhaust system.

John Bowe Intake and throttle body, K&N Pod style air cleaner

Cams, underdrives, 4.11 gears and custom tune

Car rolled up with 262 rwkw on the dyno..

The tuner says that the 4 into 1 extractors would yield a better result..

Im actually thining about putting them on to replace the set on the car at the moment.. however, im told the 4 into 1s might produce better numbers on the dyno (peak output) but will it overall be worse losing a little mid range and low end??

What are thoughts on this??

i would say stick with 4 into 2 into 1 would be way better for on the street , 4 into 1's if you hold it wide open throtal every where you drive. Dont worry about chasing numbers on a dyno the real dyno is that black tar stuff on the street and Try-y would yield you more torque and better down low revs right across your range where the 4into ones would just give you a higher top end number that you would hardly utilize....
i had 4into 1 pacies on my 393 and have now gone with the try-y.

What cams do you have?

Not sure what the cam grind is but apparently there is one grind that everyone is using in the BOSS 260.. Best overall result..

I compared two dyno graphs today... My car with mods as described above VS another BOSS 260 but with 4-1 defillipo headers.. I was surprised at results.. I know that the cars are on different dynos but the shape of the graph was what i was interested in..

My car made 261.2rwkw at 600rpm.. Power then slowly dropped off after 6000rpm to 65000rpm cutout. But torque was 510nm from 3000rpm onwards and hit peak of 565nm at 4500rpm. Further power was at 230rwkw from 4000rpm

The 4-1 extractors car made 263rwkw at 6500rpm. Power did not drop off like my car but only made an extra 2kw? But power didnt come on until later, for most of the graph down low I had around 30rwkw and 40nm torque on that car.. The 4-1 header car only matched my car from 5000rpm upwards. Under that it was a clear loser.

I also presume the cam is the same as both a crow cams and im told there is one grind everyone is using.

I can email both graphs if someone is interested in posting up and making comments.

I think you have your answer there(if the other car is identical to yours in every other way?)...4-2-1's.
I've seen tests between 4-2-1 and 4-1 pacemakers and the 4-2-1's certainly maintained the greater area under the curve. I've seen some comp cams in a 290 engine and he picked up a substantial 60hp with good torque gains too, but he didn't know which ones he had because he spat out some meaningless drivel about being "stage 2"!? It certainly sounded good.

Some people beleive the BOSS works better with 4-1 extractors. Ive seen quite a few threads on this..

Im just not sure if its worth the $$$$ to scrap my tri-ys for a set of 4 into 1s

Ive read many threads where BOSS owners swear by the 4 into 1s..

But many LS1 owners swear by the tri-ys???

The boss owners claim that the power and torque generated by the tri-ys down low and mid range is insignificant when compared to the 4 into 1s but the top end of the 4 into 1s is clearly stronger..

HM headers profess tri-ys and deflillipo swear by 4 into 1s??

"Works better where?" is really the question. Most people are still stuck in the peak hp number mentality. Primary size comes into the equation too.
I've driven a 260 with 1 7/8" 4-1's and it was doughy to say the least.
Amazingly, LS1 owners actually need more help in the torque dept than a 4V 5.4 so it stands to reason the 4-2-1 will be of benefit.

doe anyone have any evidence to support either tri y or 4 into 1s on a boss 260 motor??

can anyone provide any more insight?