ok i just put in my walbro and aluminum tid in my car and also took out the airpump..i have stock exhaust right now but that will change soon. the tid i bought was just a generic intake for a 96-00 civic. wen i matched it up with my rubber coupler i had bought that was 3 inches..its was lik half an inch maybe 1/4 inch smaller..so i guess its lik a 2 1/2-2 3/4 inch tid. i havent noticed any boost gains and i was under the impression i should be seeing about 2 lbs of boost more. could it be because my exhaust is just too restrictive.. i may be seeing lik 1/2 lb at most acording to my boost auge.. my throttle response is better though. o yea i have 1988 tubro II with a k and n cone filter

 

Could be the exhaust, could be the diamter. Could be the design. Would have to see pics. Do you have stock cats? If so, its hard to get any more boost past those sometimes.

 

You have stock exhaust? That is the reason. End of post bro

James