95 del sol questions

well i have a relly odd question...i know my car isnt a vtec as it is a sohc 1.5 del sol s...my question is...when i get it up to about 4500 it feels like i have a vtec..she starts to whine and i definately have a large power increase all the way to 6700 or so.....what., if anything would make that happen?? i have put on a high flow cat, header, cold air, and greddy muffler, but none of these things to me, would make that happen...is it possible to have a vtec and not know it?? plus it has over 220,000 miles on it!!!!!

well i have a relly odd question...i know my car isnt a vtec as it is a sohc 1.5 del sol s...my question is...when i get it up to about 4500 it feels like i have a vtec..she starts to whine and i definately have a large power increase all the way to 6700 or so.....what., if anything would make that happen?? i have put on a high flow cat, header, cold air, and greddy muffler, but none of these things to me, would make that happen...is it possible to have a vtec and not know it?? plus it has over 220,000 miles on it!!!!!
and another thing...when i bought it the guy that sold it to me said he had replaced to old ecu with a skunk2...how would i tell if he really did that or not???

it's not a VTEC... it's just the horsepower going up from 84 to 92 as you reach your middle and upper powerband. Only way to check the ecu is to remove it and open it up. If it's a skunk2, it will say so.