I know just buy large mouths, well I found some runners on a different car that are much larger than stock tpi tubes, and with a little trimming they should fit they look to be a good 1/4 inch in diameter bigger would this help much ? ..... I have an aluminum welder so fabrcation isn't hard for me, and how much larger in diameter are after market runners than stock.

 

why don't you full siamise a set and port out the flanges...do some searches, you can find a few pics....this is what i was gonna do if i kept TPI, but i didn't...but you can siamise the runners, make it so its a big oval runner, then siamese the flange, and port match the upper and lower intake...

 

because I've heard siamesing hurts lowend torque, I am looking for torque and more rpm so I think making larger runners is the way to achieve this. But I'm not sure how much more a 1/4 inch in diameter larger runners would help. I just don't like at 4,500 rpm when the motor falls on its face so I figured with some intake porting and buying a set of these larger tubes it would help my car.

 

bigger runners usually means being able to breathe in higher RPMS....and usually higher RPMS defeats the lowend end torque...so you have to find a line in between....you can't have a high revving motor with tons of lowend torque ya know...

 

Well I'll tell you that I have modified the heck out of my TPI system and I now have more torque than when it was stock. Of course I have done some other mods along the way.

I have no trouble burning the tires in first and 2nd gear. I would like to lose some more low end torque. Makes it harder to launch the car at the strip.

By the way I have fully siamesed SLP runners. Allen

 

Either of what they said but always remeber your not going to see much with them suggestions unless you get a better base. Good luck.

Id go with a full siamese. Itll take some low end out but a LTR will always keep that low end torqe. The Siamese runners and a nice base would be the inbetween line.

 

you'll see minimal gains if you only do the runners...like stated above, the only way your gonna see a substantial gain is if you do the base, the runners, and perhaps port match your upper plenum...