For real. People are so stupid about this gas mileage shit. Like the lady who spent $7,000 on a '96 Geo Metro to get an extra 10mpg over her Honda Element. Congratulations, you'll break even in about 300 years.

If money isn't an issue why are you worried about gas and mpg? Best swap, keep it stock. Go buy a scooter and and get like 80-100 per gal. Join the next trend and sport a Honda Ruckus. :p

i have a ca and its not the greatest on the milleage even just cruising down the freeway thestock t25 is always in boost so its not that great for milleage but thats not why i did the swap

gearing makes a difference as mentioned earlier with the q45 diff.

followed by people learning how to drive.

SLOW DOWN

slow acceleration + low revs + overall low speed + coasting a lot + correct gearing = MPG

I averaged in my DD (06 sentra spec v) 33mpg on the highway because I took my time at 70mph instead of going 75~80

I can imagine a lightly moded VQ with the 6 speed trans and 3.7 or lower rear gear and the correct driving can pull off some amazing numbers.

I think you would have the best luck if you go to a 3.5 rear end, and a small 200hp turbo setup to compensate for the gearing change. Tune it correctly and you should come out with more power and better gas mileage.

Is there a six speed transmission that will fit the KA or an alternative 5th gear for the KA trans?

CA tranny with the KA/SR rear end? 5th gear in the CA tranny is shorter then the KA/SR. Keeps it at a higher rpm for drivability. Swap your CA bell housing on a KS/SR tranny and you'll cruse at a lower RPM.

I'm newbie here whats a Ls1

its a 5.7 liter Pushrod v8 that can be found in 98 and up camaros, c5 corvettes, firebirds, and stuff.

350hp 350tq stock.

I have built a few. My last one a fc with a turbo ls1 made around 500 whp and got like 30 mpg.

Go with the SR DET. Factory tunes run rich to avoid detonation so just get a better tune to lean it out and you will have instant increase in MPG and more horsepower than your KA all in one reliable package.

I get 26-28 on my turbo KA, the key is a big turbo.