well not sure on measurements but for starters the intake on a eclipse is in the back.. that would have to go on the front... the eclipse heads isnt set op for a neon and you gain nothing by going with an eclipse head.. second although nice that mani cost about 6-700 what tb you gonna use. if ur a fabber why pay all that money to pay for one whn you can mod the dohc mani to work right.. the 90 bends will have no bearing on making hp.. ur boosted it wont matter.. but taking out the 90 will make it easier to use larger throttle bodies and such.. in ur case a stock setup will work fine.. although a custom setup log style or box will gain you some hp it wont be enough to notice... you start going this route and all and you start to approach the limits of the stock internals.. at 8-9 psi the stock rods will hold up to around 250hp... thru boosting... a guy i know of made 188whp through his stock internaled sohc running a crane 12 longtubes and udp a little port clean up and individual throttlebodies

 

yeah the more ive thought about it i probably am going to jus fab up a log mani for fun when i have fab class and then run it and see how it goes