Bought this car a month ago from a guy...blah blah blah. Apparently it's got a build bottom end (confirmed from someone who knows the guy) and a tune. well It's been at 20 pounds since I got it on the stock turbo and wastegate (looks stock and old as hell). Should I get a boost controller and tune it down? I'm getting some lag in higher gears and I guess spark blowout in high speeds (loud pop and fuel cut, then returns to normal). Any incite would be great thanks!
Sounds like the turbo is being pushed past efficiency (without knowing your setup). Boost controllers are antiquated, you would be better off with a DSP U7134. Need 3bar MAP and TIP if you want to keep it that high, stock sensors are geared toward 18 psi. A normal setup will spike 15-17 and hold 11-13 and yield a fairly decent lifespan for the turbo. Without supporting mods at 20 psi you're blowing hot air.
There is no way a stock turbo can hold 20 psi. It can spike more than 20 psi but will stay around 16 at upper rpm´s. Get a Diablo predator, run a log looking for knock and check your AFR´s with a wide band. If no knock and AFR´s around 11´s, enjoy your car. No need for 3 bar map/tip sensors if you are not thinking to upgrade the turbo. However, if the turbo is a BW turbo, then you will need a tune.
Stock turbos have been running 20-22psi and doing it very well for over 10years.
All my Stock turbo tunes, All Diablo tunes and every Stage 2 tunes boost 20-22psi. No issues whatsoever. Over ~22-23psi is a waste of time, imo. I've even seen several idiots crank them up to 27-28psi with little if any gain.
SrtBob911, you could have a Stage 2 but more likely is that the kid probably left a Diablo tune flashed to the car but sold the Diablo tool.
3bars and a Rescale are highly recommended when boosting over 18psi. No boost controller is ever needed for a stock turbo. the PCM and a Diablo tool is all a stock turbo ever needs.